Below are some links to useful tools for supporting prisoners.
Black and Pink’s database of prison mailing addresses. Perfect if you’re not sure exactly where to send a letter.
My Inmate Locator. A list of most state and federal inmate locators. A few of them are missing or don’t work though.
Vinelink. Another collection of state inmate locators with a snazzy clickable map. Vinelink also has some gaps, but they are mostly different gaps than My Inmate Locator. Vinelink might provide a little more information in some cases.
Maine Inmate Locator. Maine is the one state whose inmate locator isn’t on Vinelink or My Inmate Locator.
South Dakota has no inmate locator, you have to call (605) 367-5190 or (605) 367-5140.