Sources & Methodology

Research

Facts on every landmark page are verified against authoritative sources before publication, including the National Park Service, the National Register of Historic Places, the Library of Congress, the Smithsonian, state historical societies, and the institutions that manage each site. Where a fact cannot be verified, we leave it out rather than guess.

Images

We publish only public-domain, appropriately licensed, or original images. Every image records its credit, source, and license — shown in the caption beneath it. Primary image sources include:

• Library of Congress Digital Collections
• National Park Service
• Wikimedia Commons (license verified per image)
• The New York Public Library Digital Collections
• Smithsonian Open Access
• State archives and historical societies

If you believe an image is misattributed or used in error, please contact us and we’ll correct it promptly.