Throughout its history, the United States expanded its territory significantly through land purchases from foreign powers. The largest acquisition was the Louisiana Purchase in 1803, when the U.S. bought the territory from France for $15 million, gaining approximately 2.14 million km² of land. This single deal nearly doubled the size of the country and laid the foundation for U.S. expansion westward, making it one of the most impactful land transactions in modern history.
The second-largest purchase was Alaska in 1867, acquired from Russia for $7.2 million, covering around 1.52 million km². Initially criticized as “Seward’s Folly,” Alaska later proved to be a strategic and economic asset due to its vast natural resources and geopolitical importance. Today, it stands as the largest U.S. state by land area.
In third place is Texas, which became part of the United States in 1848 following a deal with Mexico, valued at $15 million and adding roughly 1.36 million km² of land. This acquisition played a major role in shaping the southern United States and strengthening U.S. influence in North America. Together, the Louisiana Purchase, Alaska acquisition, and Texas deal account for the majority of land ever purchased by the U.S., highlighting how strategic transactions helped shape the nation’s modern borders.
