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Digital Data

There is a vast amount of Digital Data available for the United States - most of the trouble simply comes down to locating it and determining whether or not it's viable to use. Below are descriptions of some of the most common data sets and web sites for data in the US.

DRGs (Digital Raster Graphics)

DRGs are scanned USGS topographic quads that come in TIFF or Mr. Sid format. They are georeferenced through "heads up" digitizing and can be acquired through CaSIL.

DRG

CalAtlas

CalAtlas Data Download

DLGs (Digital Line Graphs)

DLGs are vector representations of many of the features on USGS topographic quadrangles. These can be acquired through USGS, and represent features such as:

Example DLGs

DEMs (Digital Elevation Model)

DEMs provide elevation data in a raster format. They are available for most of the earth at 30- to 10 meter resolutions. These can be acquired through USGS Earth Explorer.

Sample DEM

Coastal Mapping (LiDAR)

California's Ocean Protection Council provides access to high resolution elevation data from LiDAR.

Coastal Mapping (LiDAR)

Data Access Viewer

DOQs and DOQQs (Digital Ortho Quads/Quarter Quads)

DOQs and DOQQs are scanned aerial photographs which have 1 meter resolution, are typically black and white, georeferenced to UTM, available for much of the US, and can be obtained through CaSIL.

Production began in 1991 and was led by USGS.

Example DOQs and DOQQs:

Digital Ortho Quads/Quarter Quads

Digital Ortho Quads/Quarter Quads 2

Digital Ortho Quads/Quarter Quads 3

NAIP (National Agriculture Imagery Program) Imagery

The acquisition of NAIP imagery began in 2003 by the USDA. The program has the intention of providing agricultural surveys for the purpose of estimating crop yields. NAIP imagery has 1 meter resolution, true color composites (RGB), some infrared products, is georeferenced to UTM (NAD83), and can be obtained through CaSIL.

LandSat Imagery (USGS and NASA)

LandSat is the longest running satellite system on the earth and has providing data since 1972. The data is now all free as well! The data is available at the USGS EarthExplorer web site.

Landsat History

LandSat 8 - March 18, 2013

Landsat 8 - Example 1

LandSat 8 - March 18, 2013

Landsat 8 - Example 2

LandSat 8 - March 18, 2013

Landsat 8 - Example 3

USGS GLOVIS - http://glovis.usgs.gov/

Glovis is another source of spatial data from the US government and some users prefer this web site to EarthExplorer.

USGS GLOVIS - Example

National Wetlands Inventory

The National Wetlands Inventory provides data on the location, condition, and characteristics of wetlands. The data is provided through the US Fish and Wildlife Service, and can be acquired from NWI.

Wetland Map - Example

 

Wetlands Data Extraction Tool

Wetlands Data Extraction Tool

Wetland Shapefile Hyperlink

Wetland Shapefile Hyperlink

NWI Mapping Code Description

NWI Mapping Code Description

Hydrologic Data

The National Hydrography Dataset (NHD)

NHD provides data on rivers, streams, canals, ditches, lakes, ponds, springs, wells, canals, pipelines, and dams. The data is based on 1:100,000 scale USGS DLG Data, and can be acquired from USGS at their NHD website.

CaSIL's Hydrography Layer for California

Hydrography data for California was digitized from 1:24,000 scale USGS Topo quads, and can be obtained from CaSIL. Just search Inland waters, then Hydrologic features.

The National Atlas (USGS)

National Atlas is no longer available! Very sad.

Land Use and Land Cover - 2 National Data sets

USGS Land Use and Land Cover (LULC)

USGS LULC data are classified images that were derived from aerial photographs and based on 1:100,000 - 1:250,000 scale USGS Topo Quads. Publications on land use and land cover can be found here.

National Land Cover Database (NLCD)

NLCD provides classifications derived from LandSat imagery from 2001 to 2011.

National Land Cover Database

National Land Cover - Classification Key

California Land Cover Data

California Land Cover Data is managed by the Department of Forestry and Fire Protection (CDF), through the Fire Resource Protection Program (FRAP). It is Multi-source Land Cover Data (v02_2) that was compiled for the Forest and Range 2003 Assessment, which can be acquired here.

California Land Cover Data

Digital Census Data

Census data can be obtained through the US Census Bureau via their TIGER (Topologically Integrated Geographic Encoding and Referencing) System. It is Spatial Data derived from the national census (household), and distributed by state, county, census track, census block, etc. Census data links geographic units (roads, hydrography, political boundaries, schools, parks, etc) to statistical data (population size, age, income, health, etc). This data can also be acquired through ArcGIS.

Census Boundary Enumeration Levels

Census Boundary Enumeration Levels

American FactFinder: US Census

American Fact Finder - Advanced Search

Census Demographics: Attribute Table

Census Demographics - Attribute Table

Test Your Knowledge

 

Additional Resources

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