Primary sources are tricky documents. They can be excellent texts to use in the classroom to improve content knowledge and build skills, but care must be taken so they promote rather than thwart learning (Eicher, 2007; Newman, 2014). A couple of preliminary steps can eliminate pitfalls and help a primary source fulfill its promise. Traditionally, sourcing meant authenticating the document by checking its provenance to ensure it is legit, meaning the document is what it purports to be (Wineburg, 1991). In recent years with digitized collections becoming more numerous, evaluating where the document was accessed has become important, as has assessing any information on the document included in the repository. This essay stresses the importance of sourcing a primary source document before using it in the classroom. This article uses "American Progress," a popular visual often used incorrectly to illustrate manifest destiny, as example when suggesting that sourcing does not end with the bibliography but also involves looking at the document and its backstory.