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.
We analyzed historical aerial photography and used dendrochronology to quantify long-term spatial and temporal patterns of narrowing and vegetation expansion, including native cottonwood (Populus...
data.gov
An official website of the GSA's Technology Transformation Services