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At least 37 records · Page 2Linked to original sources
USGS2009

Integrating disparate lidar datasets for a regional storm tide inundation analysis of Hurricane Katrina

Hurricane Katrina was one of the largest natural disasters in U.S. history. Due to the sheer size of the affected areas, an unprecedented regional analysis at very high resolution and accuracy was needed to properly quantify and understand the effects of the hurricane and the storm tide. Many disparate sources of lidar data were acquired and processed for varying environmental reasons by pre- and post-Katrina projects. The datasets were in several formats and projections and were processed to varying phases of completion, and as a result the task of producing a seamless digital elevation dataset required a high level of coordination, research, and revision. To create a seamless digital elevation dataset, many technical issues had to be resolved before producing the desired 1/9-arc-second (3meter) grid needed as the map base for projecting the Katrina peak storm tide throughout the affected coastal region. This report presents the methodology that was developed to construct seamless digital elevation datasets from multipurpose, multi-use, and disparate lidar datasets, and describes an easily accessible Web application for viewing the maximum storm tide caused by Hurricane Katrina in southeastern Louisiana, Mississippi, and Alabama.

Journal of Coastal Research↗
USGS2013

Development of a reproducible method for determining quantity of water and its configuration in a marsh landscape

Coastal Louisiana is a dynamic and ever-changing landscape. From 1956 to 2010, over 3,734 km 2 of Louisiana's coastal wetlands have been lost due to a combination of natural and human-induced activities. The resulting landscape constitutes a mosaic of conditions from highly deteriorated to relatively stable with intact landmasses. Understanding how and why coastal landscapes change over time is critical to restoration and rehabilitation efforts. Historically, changes in marsh pattern (i.e., size and spatial distribution of marsh landmasses and water bodies) have been distinguished using visual identification by individual researchers. Difficulties associated with this approach include subjective interpretation, uncertain reproducibility, and laborious techniques. In order to minimize these limitations, this study aims to expand existing tools and techniques via a computer-based method, which uses geospatial technologies for determining shifts in landscape patterns. Our method is based on a raster framework and uses landscape statistics to develop conditions and thresholds for a marsh classification scheme. The classification scheme incorporates land and water classified imagery and a two-part classification system: (1) ratio of water to land, and (2) configuration and connectivity of water within wetland landscapes to evaluate changes in marsh patterns. This analysis system can also be used to trace trajectories in landscape patterns through space and time. Overall, our method provides a more automated means of quantifying landscape patterns and may serve as a reliable landscape evaluation tool for future investigations of wetland ecosystem processes in the northern Gulf of Mexico.

Louisiana↗
USGS2002

Basis and methods of NASA airborne topographic mapper lidar surveys for coastal studies

This paper provides an overview of the basic principles of airborne laser altimetry for surveys of coastal topography, and describes the methods used in the acquisition and processing of NASA Airborne Topographic Mapper (ATM) surveys that cover much of the conterminous US coastline. This form of remote sensing, also known as "topographic lidar", has undergone extremely rapid development during the last two decades, and has the potential to contribute within a wide range of coastal scientific investigations. Various airborne laser surveying (ALS) applications that are relevant to coastal studies are being pursued by researchers in a range of Earth science disciplines. Examples include the mapping of "bald earth" land surfaces below even moderately dense vegetation in studies of geologic framework and hydrology, and determination of the vegetation canopy structure, a key variable in mapping wildlife habitats. ALS has also proven to be an excellent method for the regional mapping of geomorphic change along barrier island beaches and other sandy coasts due to storms or long-term sedimentary processes. Coastal scientists are adopting ALS as a basic method in the study of an array of additional coastal topics. ALS can provide useful information in the analysis of shoreline change, the prediction and assessment of landslides along seacliffs and headlands, examination of subsidence causing coastal land loss, and in predicting storm surge and tsunami inundation.

Journal of Coastal Research↗
USGS2021

Improving ESRI ArcGIS performance of coastal and seafloor analysis with the Python multiprocessing module

Coastal research frequently involves the use of a GIS to analyze large areas for changes in response to major weather events, human action, and other factors. The GIS workflows used to conduct these analyses can be complex and sometimes require multiple days to complete. Long runtimes often exist even on modern high-powered workstations if the GIS software does not use parallel computing techniques, which prevents it from fully utilizing the capabilities of multicore processors. If a GIS application supports a programming interface that allows geoprocessing tools to be called from an external program, then GIS workflows can use parallel functionality embedded in that programming language to divide the load of a large workflow among multiple child processes. In ArcMap and ArcGIS Pro, this technique can be implemented by using the Python programming interface and the multiprocessing module in Python to run geoprocessing tools in child processes. This method was used in the Seafloor Elevation Change Analysis Tool (SECAT), a Python script written for ArcMap and ArcGIS Pro that calculates changes in seafloor elevation over time using two different digital elevation models. Running SECAT with between one and eight child processes on two different datasets improved execution times by at least a factor of 2.4. These results demonstrate that using the Python multiprocessing module can significantly accelerate a variety of time-consuming workflows.

Journal of Coastal Research↗
USGS2013

Consideration of vertical uncertainty in elevation-based sea-level rise assessments: Mobile Bay, Alabama case study

The accuracy with which coastal topography has been mapped directly affects the reliability and usefulness of elevationbased sea-level rise vulnerability assessments. Recent research has shown that the qualities of the elevation data must be well understood to properly model potential impacts. The cumulative vertical uncertainty has contributions from elevation data error, water level data uncertainties, and vertical datum and transformation uncertainties. The concepts of minimum sealevel rise increment and minimum planning timeline, important parameters for an elevation-based sea-level rise assessment, are used in recognition of the inherent vertical uncertainty of the underlying data. These concepts were applied to conduct a sea-level rise vulnerability assessment of the Mobile Bay, Alabama, region based on high-quality lidar-derived elevation data. The results that detail the area and associated resources (land cover, population, and infrastructure) vulnerable to a 1.18-m sea-level rise by the year 2100 are reported as a range of values (at the 95% confidence level) to account for the vertical uncertainty in the base data. Examination of the tabulated statistics about land cover, population, and infrastructure in the minimum and maximum vulnerable areas shows that these resources are not uniformly distributed throughout the overall vulnerable zone. The methods demonstrated in the Mobile Bay analysis provide an example of how to consider and properly account for vertical uncertainty in elevation-based sea-level rise vulnerability assessments, and the advantages of doing so.

Alabama↗
USGS2012

Synthesis study of an erosion hot spot, Ocean Beach, California

A synthesis of multiple coastal morphodynamic research efforts is presented to identify the processes responsible for persistent erosion along a 1-km segment of 7-km-long Ocean Beach in San Francisco, California. The beach is situated adjacent to a major tidal inlet and in the shadow of the ebb-tidal delta at the mouth of San Francisco Bay. Ocean Beach is exposed to a high-energy wave climate and significant alongshore variability in forcing introduced by varying nearshore bathymetry, tidal forcing, and beach morphology ( e.g. , beach variably backed by seawall, dunes, and bluffs). In addition, significant regional anthropogenic factors have influenced sediment supply and tidal current strength. A variety of techniques were employed to investigate the erosion at Ocean Beach, including historical shoreline and bathymetric analysis, monthly beach topographic surveys, nearshore and regional bathymetric surveys, beach and nearshore grain size analysis, two surf-zone hydrodynamic experiments, four sets of nearshore wave and current experiments, and several numerical modeling approaches. Here, we synthesize the results of 7 years of data collection to lay out the causes of persistent erosion, demonstrating the effectiveness of integrating an array of data sets covering a huge range of spatial scales. The key findings are as follows: anthropogenic influences have reduced sediment supply from San Francisco Bay, leading to pervasive contraction ( i.e. , both volume and area loss) of the ebb-tidal delta, which in turn reduced the regional grain size and modified wave focusing patterns along Ocean Beach, altering nearshore circulation and sediment transport patterns. In addition, scour associated with an exposed sewage outfall pipe causes a local depression in wave heights, significantly modifying nearshore circulation patterns that have been shown through modeling to be key drivers of persistent erosion in that area.

California↗
USGS2016

Depth calibration and validation of the Experimental Advanced Airborne Research Lidar, EAARL-B

The original National Aeronautics and Space Administration (NASA) Experimental Advanced Airborne Research Lidar (EAARL), was extensively modified to increase the spatial sampling density and improve performance in water ranging from 3–44 m. The new (EAARL-B) sensor features a 300% increase in spatial density, which was achieved by optically splitting each laser pulse into 3 pulses spatially separated by 1.6 m along the flight track and 2.0 m across-track on the water surface when flown at a nominal altitude of 300 m. Improved depth capability was achieved by increasing the total peak laser power by a factor of 10, and incorporating a new “deep-water” receiver, optimized to exclusively receive refracted and scattered light from deeper water (15–44 m). Two clear-water missions were conducted to determine the EAARL-B depth calibration coefficients. The calibration mission was conducted over the U.S. Navy’s South Florida Testing Facility (SFTF), an established lidar calibration range located in the coastal waters southeast of Fort Lauderdale, Florida. A second mission was conducted over Lang Bank, St. Croix, U.S. Virgin Islands. The EAARL-B survey was spatially and temporally coincident with multibeam sonar surveys conducted by the National Oceanic and Atmospheric Administration (NOAA) ship Nancy Foster. The NOAA depth data range from 10–100 m, whereas the EAARL-B captured data from 0–41 m. Coefficients derived from the SFTF calibration mission were used to correct the EAARL-B data from both missions. The resulting calibrated EAARL-B data were then compared with the original reference dataset, a jet-ski-based single beam sonar dataset from the SFTF site, and the deeper NOAA data from St. Croix. Additionally, EAARL-B depth accuracy was evaluated by comparing the depth results to International Hydrographic Organization (IHO) standards. Results show good agreement between the calibrated EAARL-B data and all three reference datasets, with 95% confidence levels well within the maximum allowable total vertical uncertainty for IHO Order 1 surveys.

Journal of Coastal Research↗
USGS1994

Historical shoreline mapping (I): improving techniques and reducing positioning errors

A critical need exists among coastal researchers and policy-makers for a precise method to obtain shoreline positions from historical maps and aerial photographs. A number of methods that vary widely in approach and accuracy have been developed to meet this need. None of the existing methods, however, address the entire range of cartographic and photogrammetric techniques required for accurate coastal mapping. Thus, their application to many typical shoreline mapping problems is limited. In addition, no shoreline mapping technique provides an adequate basis for quantifying the many errors inherent in shoreline mapping using maps and air photos. As a result, current assessments of errors in air photo mapping techniques generally (and falsely) assume that errors in shoreline positions are represented by the sum of a series of worst-case assumptions about digitizer operator resolution and ground control accuracy. These assessments also ignore altogether other errors that commonly approach ground distances of 10 m. This paper provides a conceptual and analytical framework for improved methods of extracting geographic data from maps and aerial photographs. We also present a new approach to shoreline mapping using air photos that revises and extends a number of photogrammetric techniques. These techniques include (1) developing spatially and temporally overlapping control networks for large groups of photos; (2) digitizing air photos for use in shoreline mapping; (3) preprocessing digitized photos to remove lens distortion and film deformation effects; (4) simultaneous aerotriangulation of large groups of spatially and temporally overlapping photos; and (5) using a single-ray intersection technique to determine geographic shoreline coordinates and express the horizontal and vertical error associated with a given digitized shoreline. As long as historical maps and air photos are used in studies of shoreline change, there will be a considerable amount of error (on the order of several meters) present in shoreline position and rate-of- change calculations. The techniques presented in this paper, however, provide a means to reduce and quantify these errors so that realistic assessments of the technological noise (as opposed to geological noise) in geographic shoreline positions can be made.

Journal of Coastal Research↗
USGS2006

A search for scale in sea-level studies

Many researchers assume a proportional relationship among the atmospheric CO2 concentration, temperature, and sea level. Thus, the rate of sea-level rise should increase in concert with the documented exponential increase in CO2. Although sea surface temperature has increased in places over the past century and short-term sea level rose abruptly during the 1990s, it is difficult to demonstrate a proportional relationship using existing geologic or historic records. Tide gauge records in the United States cover too short a time interval to verify acceleration in the rate of sea-level rise, although multicentury tide gauge and staff records from the Netherlands and Sweden suggest a mid-19th-century acceleration in sea-level rise. Reconstructions of sea-level changes for the past 1000 years derived using benthic foraminifer data from salt marshes along the East Coast of the United States suggest an increased rate of relative sea-level rise beginning in the 1600s. Geologic records of relative sea-level rise for the past 6000 years are available for several sites along the US East Coast from 14C-dated basal peat below salt marshes and estuarine sediments. When these three scales of sea-level variation are integrated, adjusted for postglacial isostatic movement, and replotted, the range of variation in sea level suggested by basal peat ages is within ??1 meter of the long-term trend. The reconstruction from Long Island Sound data shows a linear rise in sea level beginning in the mid-1600s at a rate consistent with the historic record of mean high water. Long-term tide gauge records from Europe and North America show similar trends since the mid-19th century. There is no clear proportional exponential increase in the rate of sea-level rise. If proportionality exists among sea level, atmospheric CO2, and temperature, there may be a significant time lag before an anthropogenic increase in the rate of sea-level rise occurs.

Journal of Coastal Research↗
USGS2005

Quaternary geomorphology and modern coastal development in response to an inherent geologic framework: An example from Charleston, South Carolina

Coastal landscapes evolve over wide-ranging spatial and temporal scales in response to physical and biological processes that interact with a wide range of variables. To develop better predictive models for these dynamic areas, we must understand the influence of these variables on coastal morphologies and ultimately how they influence coastal processes. This study defines the influence of geologic framework variability on a classic mixed-energy coastline, and establishes four categorical scales of spatial and temporal influence on the coastal system. The near-surface, geologic framework was delineated using high-resolution seismic profiles, shallow vibracores, detailed geomorphic maps, historical shorelines, aerial photographs, and existing studies, and compared to the long- and short-term development of two coastal compartments near Charleston, South Carolina. Although it is clear that the imprint of a mixed-energy tidal and wave signal (basin-scale) dictates formation of drumstick barriers and that immediate responses to wave climate are dramatic, island size, position, and longer-term dynamics are influenced by a series of inherent, complex near-surface stratigraphic geometries. Major near-surface Tertiary geometries influence inlet placement and drainage development (island-scale) through multiple interglacial cycles and overall channel morphology (local-scale). During the modern marine transgression, the halo of ebb-tidal deltas greatly influence inlet region dynamics, while truncated beach ridges and exposed, differentially erodable Cenozoic deposits in the active system influence historical shoreline dynamics and active shoreface morphologies (block-scale). This study concludes that the mixed-energy imprint of wave and tide theories dominates general coastal morphology, but that underlying stratigraphic influences on the coast provide site-specific, long-standing imprints on coastal evolution.

Journal of Coastal Research↗
USGS2005

A note on the comparative turbidity of some estuaries of the Americas

Field data from 27 estuaries of the Americas are used to show that, in broad terms, there is a large difference in turbidity between the analyzed east and west-coast estuaries and that tidal range and tidal length have an important influence on that turbidity. Generic, numerical sediment-transport modeling is used to illustrate this influence, which exists over a range of space scales from, e.g., the Rogue River Estuary (few km, few mg l-1) to the Bay of Fundy (hundreds of km, few g l-1). The difference in Pacific and Atlantic seaboard estuarine turbidity for the analyzed estuaries is ultimately related to the broad-scale geomorphology of the two continents.

Journal of Coastal Research↗
USGS2005

Seasonal to interannual morphodynamics along a high-energy dissipative littoral cell

A beach morphology monitoring program was initiated during summer 1997 along the Columbia River littoral cell (CRLC) on the coasts of northwest Oregon and southwest Washington, USA. This field program documents the seasonal through interannual morphological variability of these high-energy dissipative beaches over a variety of spatial scales. Following the installation of a dense network of geodetic control monuments, a nested sampling scheme consisting of cross-shore topographic beach profiles, three-dimensional topographic beach surface maps, nearshore bathymetric surveys, and sediment size distribution analyses was initiated. Beach monitoring is being conducted with state-of-the-art real-time kinematic differential global positioning system survey methods that combine both high accuracy and speed of measurement. Sampling methods resolve variability in beach morphology at alongshore length scales of approximately 10 meters to approximately 100 kilometers and cross-shore length scales of approximately 1 meter to approximately 2 kilometers. During the winter of 1997/1998, coastal change in the US Pacific Northwest was greatly influenced by one of the strongest El Nin??o events on record. Steeper than typical southerly wave angles resulted in alongshore sediment transport gradients and shoreline reorientation on a regional scale. The La Nin??a of 1998/1999, dominated by cross-shore processes associated with the largest recorded wave year in the region, resulted in net beach erosion along much of the littoral cell. The monitoring program successfully documented the morphological response to these interannual forcing anomalies as well as the subsequent beach recovery associated with three consecutive moderate wave years. These morphological observations within the CRLC can be generalized to explain overall system patterns; however, distinct differences in large-scale coastal behavior (e.g., foredune ridge morphology, sandbar morphometrics, and nearshore beach slopes) are not readily explained or understood.

Journal of Coastal Research↗
USGS2004

Importance of storm events in controlling ecosystem structure and function in a Florida Gulf Coast estuary

From 8/95 to 2/01, we investigated the ecological effects of intra- and inter-annual variability in freshwater flow through Taylor Creek in southeastern Everglades National Park. Continuous monitoring and intensive sampling studies overlapped with an array of pulsed weather events that impacted physical, chemical, and biological attributes of this region. We quantified the effects of three events representing a range of characteristics (duration, amount of precipitation, storm intensity, wind direction) on the hydraulic connectivity, nutrient and sediment dynamics, and vegetation structure of the SE Everglades estuarine ecotone. These events included a strong winter storm in November 1996, Tropical Storm Harvey in September 1999, and Hurricane Irene in October 1999. Continuous hydrologic and daily water sample data were used to examine the effects of these events on the physical forcing and quality of water in Taylor Creek. A high resolution, flow-through sampling and mapping approach was used to characterize water quality in the adjacent bay. To understand the effects of these events on vegetation communities, we measured mangrove litter production and estimated seagrass cover in the bay at monthly intervals. We also quantified sediment deposition associated with Hurricane Irene's flood surge along the Buttonwood Ridge. These three events resulted in dramatic changes in surface water movement and chemistry in Taylor Creek and adjacent regions of Florida Bay as well as increased mangrove litterfall and flood surge scouring of seagrass beds. Up to 5 cm of bay-derived mud was deposited along the ridge adjacent to the creek in this single pulsed event. These short-term events can account for a substantial proportion of the annual flux of freshwater and materials between the mangrove zone and Florida Bay. Our findings shed light on the capacity of these storm events, especially when in succession, to have far reaching and long lasting effects on coastal ecosystems such as the estuarine ecotone of the SE Everglades.

Journal of Coastal Research↗
USGS2005

Historical shoreline changes along the US Gulf of Mexico: A summary of recent shoreline comparisons and analyses

The US Geological Survey is systematically analyzing historical shoreline changes along open-ocean sandy shores of the United States. This National Assessment of Shoreline Change Project is developing standard repeatable methods for mapping and analyzing shoreline movement so that internally consistent updates can periodically be made to record coastal erosion and land loss along US shores. Recently, shoreline change maps and a report were published for states bordering the Gulf of Mexico. Long-term and short-term average rates of change were calculated by comparing three historical shorelines (1800s, 1930s, 1970s) with an operational mean high water shoreline derived from lidar (light detection and ranging) surveys (post-1998). The rates of change, statistical uncertainties, original shorelines, and complementary geographic information system layers, such as areas of beach nourishment, are available on an Internet Map Server (IMS). For the Gulf of Mexico region, rates of erosion are generally highest in Louisiana along barrier island and headland shores associated with the Mississippi delta. Erosion also is rapid along some barrier islands and headlands in Texas, whereas barrier islands in Mississippi are migrating laterally. Highest rates of erosion in Florida are generally localized around tidal inlets. The most stable Gulf beaches generally are along the west coast of Florida, where low wave energy and frequent beach nourishment minimize erosion. Some long beach segments in Texas have accreted as a result of net longshore drift convergence and around tidal inlets that have been stabilized by long jetties. Individuals and some communities have attempted to mitigate the effects of erosion by emplacement of coastal structures, but those efforts largely have been abandoned in favor of periodic beach nourishment.

Journal of Coastal Research↗
USGS2007

Spatial trends in marsh sediment deposition within a microtidal creek system, Waccasassa Bay, Florida

Marsh surface deposition, suspended sediment concentrations, tidal hydrodynamics, and marsh surface characteristics were measured within a tidal creek system of a west-central Florida, microtidal, open marine Juncus roemerianus marsh to examine the depositional relationship between a creek system and the surrounding marsh during nonstorm conditions. Results suggest that short-term marsh deposition is highly episodic with deposition showing an inverse relationship with marsh surface inundation. Deposition was greatest at marsh sites adjacent to secondary creek segments over all examined timescales. Variations in hydroperiod, time–velocity asymmetry, vegetation density, and sediment availability could not explain the observed differences in short-term deposition.

Florida↗
USGS2005

Quantifying the rapid evolution of a nourishment project with video imagery

Spatially and temporally high-resolution video imagery was combined with traditional surveyed beach profiles to investigate the evolution of a rapidly eroding beach nourishment project. Upham Beach is a 0.6-km beach located downdrift of a structured inlet on the west coast of Florida. The beach was stabilized in seaward advanced position during the 1960s and has been nourished every 4-5 years since 1975. During the 1996 nourishment project, 193,000 m 3 of sediment advanced the shoreline as much as 175 m. Video images were collected concurrent with traditional surveys during the 1996 nourishment project to test video imaging as a nourishment monitoring technique. Video imagery illustrated morphologic changes that were unapparent in survey data. Increased storminess during the second (El Nin??o) winter after the 1996 project resulted in increased erosion rates of 0.4 m/d (135.0 m/y) as compared with 0.2 m/d (69.4 m/y) during the first winter. The measured half-life, the time at which 50% of the nourished material remains, of the nourishment project was 0.94 years. A simple analytical equation indicates reasonable agreement with the measured values, suggesting that project evolution follows a predictable pattern of exponential decay. Long-shore planform equilibration does not occur on Upham Beach, rather sediment diffuses downdrift until 100% of the nourished material erodes. The wide nourished beach erodes rapidly due to the lack of sediment bypassing from the north and the stabilized headland at Upham Beach that is exposed to wave energy.

Journal of Coastal Research↗
USGS2006

Comparing mean high water and high water line shorelines: Should prosy-datum offsets be incorporated into shoreline change analysis?

More than one type of shoreline indicator can be used in shoreline change analyses, and quantifying the effects of this practice on the resulting shoreline change rates is important. Comparison of three high water line (proxy-based) shorelines and a mean high water intercept (datum-based) shoreline collected from simultaneous aerial photographic and lidar surveys of a relatively steep reflective beach (tan ?? = 0.07), which experiences a moderately energetic wave climate (annual average Hs = 1.2 m), reveals an average horizontal offset of 18.8 m between the two types of shoreline indicators. Vertical offsets are also substantial and are correlated with foreshore beach slope and corresponding variations in wave runup. Incorporating the average horizontal offset into both a short-term, endpoint shoreline change analysis and a long-term, linear regression analysis causes rates to be shifted an average of -0.5 m/y and -0.1 m/y, respectively. The rate shift increases with increasing horizontal offset and decreasing measurement intervals and, depending on the rapidity of shoreline change rates, is responsible for varying degrees of analysis error. Our results demonstrate that under many circumstances, the error attributable to proxy-datum offsets is small relative to shoreline change rates and thus not important. Furthermore, we find that when the error associated with proxy-datum offsets is large enough to be important, the shoreline change rates themselves are not likely to be significant. A total water level model reveals that the high water line digitized by three independent coastal labs for this study was generated by a combination of large waves and a high tide several days before the collection of aerial photography. This illustrates the complexity of the high water line as a shoreline indicator and calls into question traditional definitions, which consider the high water line a wetted bound or "marks left by the previous high tide.".

Journal of Coastal Research↗
USGS2007

Shoreline change as a proxy for subaerial beach volume change

It is difficult and expensive to calculate changes in sediment volume for large sections of sandy beaches. Shoreline change could be a useful proxy for volume change because it can be collected quickly and relatively easily over long distances. In this paper, we summarize several studies that find a high correlation between shoreline change and subaerial volume change. We also examine three new data sets. On Cape Cod, Massachusetts, the correlation coefficients between the time series of shoreline change and subaerial volume change at two locations are 0.73 and 0.96. On Assateague Island, the correlation coefficient between along-coast variations in shoreline change and subaerial volume change is 0.71. On the Outer Banks of North Carolina, the average correlation coefficient between temporal variations in shoreline change and subaerial volume change is 0.84. For spatial variations, the average correlation coefficient is 0.88. It is therefore concluded that shoreline change is a useful proxy for subaerial volume change.

Massachusetts, Maryland, North Carolina, Virginia↗