National Recreation Trails Database – This is a great source! From the site: “National Recreation Trails (NRTs) provide for numerous outdoor recreation activities in a variety of urban, rural, and remote areas. Over 1,200 trails in [all 50 states] available for public use and ranging from less than a mile to 485 miles in length, have been designated as NRTs on federal, state, municipal, and privately owned lands.”
Go to their basic search page, choose your state and select “pedestrian – walking/hiking/running” from the Trail Use choices. You can even narrow it down to county. Although accessibility is not always addressed in the descriptions, contact information including phone numbers is given to help you learn if the trail is appropriate for you.