2 Sep 2025

National Hydrography Dataset (NHD) Flowline

The National Hydrography Dataset (NHD) is used to portray surface water. The NHD represents the drainage network with features such as rivers, streams, canals, lakes, ponds, coastline, etc. The principal components of the NHD are:

  • NHDFlowline: This is the fundamental flow network consisting predominantly of stream/river and artificial path vector features. It represents the spatial geometry, carries the attributes, models the water flow, and contains linear referencing measures for locating events on the network. Additional NHDFlowline features are canal/ditch, pipeline, connector, underground conduit, and coastline.
  • NHDArea: This feature class contains many additional features of water polygons. One of the more important is the stream/river feature. It represents the aerial extent of the water in a wide stream/river with a basic set of attributes. They typically contain NHDFlowline artificial paths that are used to model the stream/river. Artificial path carries the critical attributes of the stream/river, whereas NHDArea represents the geometric extent.
  • NHDWaterbody: Basic waterbodies such as lake/pond features are represented here. They portray the spatial geometry and the attributes of the feature. These water polygons may contain NHDFlowline artificial paths to allow the representation of water flow. Other NHDWaterbody features are swamp/marsh, reservoir, playa, estuary, and ice mass.
2 Sep 2025

FEMA Flood Hazard Zones

The Flood Hazard Zones are extracted from the National Flood Hazard Layer, which is a database that contains FEMA’s flood hazard map data. The database contains flood hazard information and supporting data used to develop the information. The primary flood hazard classification is indicated in the Flood Hazard Zones layer.

Flood zones are geographic areas that FEMA has defined according to varying levels of flood risk and type of flooding. For complete information about different flood zone designations, please visit the Definitions of FEMA Flood Zones web page.

Flood Hazard Zone Descriptions:
  Floodway: The stream channel and that portion of the adjacent floodplain which must remain open to permit passage of the base flood.
  1% Annual Chance Flood Zone: The 100-year or base floodplain.
  0.2% Annual Chance Flood Zone: Area of moderate flood hazard, usually the area between the limits of the 100-year and 500-year floodplains, but also shallow flooding areas (< 1 foot) or flood zones for small drainage areas (< 1 square mile).
  Area with Reduced Risk Due to Levee: Areas protected by levees from the 100-year flood.
  1% Annual Chance Future Considerations: The 100-year floodplain based on anticipated future land-use conditions.
  Area of Undetermined Hazard: Area of undetermined but possible flood hazard, typically occurring in counties with partial flood studies.

This information was acquired by state-level release February, 2020. Data release dates by state range from December 07, 2016 (Vermont) to February 12, 2020 (Utah).

2 Sep 2025

Suicide Mortality for 2015-19 by County

This layer displays suicide mortality rates from the CDC’s National Vital Statistics System – Mortality database. Data are 5-year aggregates for 2015-19 and grouped by ICD-10 codes.

2 Sep 2025

Fatal Motor Vehicle Crashes by County, 2014-2018

This layer displays the number and rate of fatalities from motor vehicle crashes occurring between 2015 and 2019, aggregated by county. Unlike typical mortality data, this data layer represents the location of the fatal crash, and not the county of the decedent’s residence.

2 Sep 2025

Residential Vacancies – 2020 Q4

This layer displays residential vacancy rates and total residential vacancies in census tracts across the United States. Vacancy rates are reported quarterly.

2 Sep 2025

Cancer Mortality for 2015-19 by County

This layer displays cancer mortality rates from the CDC’s National Vital Statistics System – Mortality database. Data are 5-year aggregates for 2015-19 and grouped by ICD-10 codes.