Your local library can have some pretty amazing resources. It all depends on their collections management, donations they may have received or their special collections focus.
University libraries make it their mission to collect local history, usually State history and some family history (especially of famous local celebrities). Their special collections can be a treasure trove of local primary sources, historical collections, maps and other one of a kind finds.
Same collection possibilities as our local libraries. These are outside the DFW Metroplex area.
National Archives and the Library of Congress are the keepers of our nation's history. You bet they have primary documents, official government records, maps and other resources. And sometimes they have better funding to digitize these items so you can search online.