The US Forest Service collects urban forest data from across the United States based on top-down aerial approaches and bottom-up field data collection. This site links to various data sets and reports for urban forest data in the United States at the state level, county level, county subdivision level and local community or place level. Please note that other, more recent data may be available on other sites. Check with your local tree group or with your regional planning organization.
Publications & Data, US Forest ServiceView Resource