The power of photography goes beyond capturing a specific moment: it can help tell the story of entire countries and peoples. The art form was developed in the 19th century, and ever since then American history has been marked by iconic moments recorded for posterity, some uplifting and inspiring and some despairing and tragic. All these pictures have in some way left their mark on the national psyche.

Click through this gallery to explore some of the most powerful images that have helped define the United States...