Neonta Williams (left) shares family letters dating back to 1901 with preservationist Kimberly Peach during the Smithsonian's Save our African American Treasures program at the Birmingham Civil Rights Institute. Peach advises her to use archive-quality polyester sleeves to protect the fragile papers, rather than store them in a zip-lock bag. Debbie Elliott/NPR hide caption

itoggle caption Debbie Elliott/NPR

Many institutions have their archives stored on CDs — but the discs aren't as stable as once thought. There is no average life span for a CD, says preservationist Michele Youket, "because there is no average disc." Sarah Tilotta/NPR hide caption

itoggle caption Sarah Tilotta/NPR

Geneva Post Office in Geneva, Ill., with no clear disposition review process in place, hundreds of these historic civic buildings may be endangered by U.S. Postal Service cost cutting, including this one. Matthew Gilson/National Trust for Historic Preservation hide caption

itoggle caption Matthew Gilson/National Trust for Historic Preservation