Watch the USA Grow, State by State

The Library of Congress has launched a new animated map, The United States at a Glance, that lets you literally watch the nation grow

At its core, the map is a powerful educational resource, allowing you to click on any point to access the foundational legal documents that established, admitted, or incorporated that state or territory. Much of the legal content is drawn from the Library’s massive Statutes at Large collection.

But the real magic for map enthusiasts is the timeline feature. Press play on the map's timeline control and you can observe an animation of the United States expanding based on the official date each state was admitted to the Union. If you love historical maps then click on a state. This will open a pop-up window showcasing vintage maps from the Library’s Geography & Map Division, alongside information about when the state was admitted into the Union.

The Library of Congress' animated map shows how the United States spread westward across North America. As the country expanded, over time, the mean population center of the United States has also shifted to the west. The United States Census Bureau's map Mean Center of Population for the United States: 1790 to 2020 visualizes this journey by plotting the geographic balance point of the nation's population for every census year since 1790, demonstrating a clear, corresponding drift to the west (and slightly south) that parallels the territorial growth.