The 10-Digit Hydrologic Units, a component of the Watershed Boundary Dataset (WBD), depict the fifth level hydrologic subdivision of the United States. A hydrologic unit can accept surface water from upstream drainage areas and may define a drainage area with single or multiple outlet points. A 10-digit hydrologic unit, or watershed, divides sub-basins into smaller management areas. There are 18,679 10-digit hydrologic units with an average size of 226 square miles (585 sq. km.).
Watershed Boundary Dataset, 6-Digit Hydrologic Units
The 6-Digit Hydrologic Units, a component of the Watershed Boundary Dataset (WBD), depict the third level hydrologic subdivision of the United States. A 6-digit hydrologic unit may subdivide a 4-digit hydrologic unit or may be equivalent. There are 401 6-digit hydrologic units with an average size of 10,486 square miles (27,159 sq. km.).
Watershed Boundary Dataset, 4-Digit Hydrologic Units
The 4-Digit Hydrologic Units, a component of the Watershed Boundary Dataset (WBD), depict the second level hydrologic subdivision of the United States. A 4-digit hydrologic unit includes the area drained by a river system, a reach of a river and its tributaries in that reach, a closed basin(s), or a group of streams forming a coastal drainage area. There are 240 4-digit hydrologic units with an average size of 17,521 square miles (45,378 sq. km.).
Location Affordability Index for Family at AMI
This layer displays the estimated percentage of household income for housing and transportation for a family earning the Area Median Income (AMI). The expected values for housing and transportation are modeled by HUD using data from the US Census Bureau and the US Department of Transportation, including:
- The average household size for a family earning AMI in the neighborhood
- The average number of workers, vehicles, and vehicle miles traveled for a family in the neighborhood
- The average utility and rental costs or average utility and mortgage costs for a housing unit to accommodate the family size above
- The proportion of housing units that are either rentals or owner-occupied in the neighborhood
Note: The LAI does not predict what families are actually paying to live in a particular area, but rather what a family would pay (either in USD or as a percentage of income) if average or reasonable housing and commuting conditions for a particular neighborhood were achieved.
Drought Severity, 2017-2019
This layer displays the percentage of weeks in Any Drought based on analysis of US Drought Monitor weekly drought data files for years 2017-2019.
Location Affordability Index for Family Below AMI
This layer displays the estimated monthly cost for housing and transportation for a low-income, single-parent family (earning 50% of the Area Median Income). The values for housing and transportation are modeled by HUD using data from the US Census Bureau and the US Department of Transportation, including:
- The average household size for a single-parent family earning 50% AMI in the neighborhood
- The average number of workers, vehicles, and vehicle miles traveled for a family in the neighborhood
- The average utility and rental costs or average utility and mortgage costs for a housing unit to accommodate the family size above
- The proportion of housing units that are either rentals or owner-occupied in the neighborhood
Note: The LAI does not predict what families earning 50% AMI are actually paying to live in a particular area, but rather what a family would pay (either in USD or as a percentage of income) if average or reasonable housing and commuting conditions for a particular neighborhood were achieved.
Uninsured Population by County
Layer displays information about the insurance status of the population age 0-64. The data are from the 2018 Small Area Health Insurance Estimates, released by the US Census Bureau on April 09, 2020.
Wildfire Perimeters
The layer displays historic wildland fire perimeters. The Geospatial Multi-Agency Coordination group, or GeoMAC, is an internet-based mapping tool originally designed for fire managers to access online maps of current fire locations and perimeters in the U.S. Perimeters are submitted to GeoMAC by field offices and made available to the public. Perimeter data is not the final or official perimeter for any incident and is provided for informational purposes only. The final official perimeter should be obtained from the host unit which can be determined by looking at the Unit ID for any specific fire.
Data from the 2020 County Health Rankings are here!
Data and maps from the 2020 County Health Rankings are now available! Click the map below to view the rank and underlying data for Premature Death, or search for additional updates by searching the Map Room for the term “CHR 2020”.
Physiographic Section Regions
This is a polygon coverage of Physiographic Divisions in the
conterminous United States. It was automated from Fenneman’s
1:7,000,000-scale map, “Physical Divisions of the United
States,” which is based on eight major 1946 divisions, 25 provinces,
and 86 sections representing distinctive areas having common
topography, rock types and structure, and geologic and
geomorphic history.