Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock ( ) or https://
means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Detailed tables (and some maps) at the county level of aggregation supporting figures and tables from Titus, James. G. "Population in floodplains or close to sea level increased in US but declined...
data.gov
An official website of the GSA's Technology Transformation Services