Click here for the official Forest Service volunteer page.
Passport in Time is a volunteer program for archaeology and historic preservation program of the Forest Service. This website explains the program and lists available projects and includes information about the application process.
Here’s a handy site for information, including the application process, for volunteering in your National Forests.
You can search for a range of government volunteer opportunities at this site. The search can be filtered by agency, keyword, state or type of job.