Louisiana, California, Alaska and more: Top 8 territorial purchases made by the United States

US President Donald Trump’s recent assertion that the United States should ‘own’ Greenland to counter Russian and Chinese influence has revived interest in America’s historic territorial purchases. Trump suggested the US might pursue the acquisition ‘the easy way’ or ‘the hard way’, though Denmark and Greenland have firmly rejected the idea. The current debate echoes earlier eras when the United States expanded its territory through negotiated purchases, events that profoundly shaped the nation’s map.

In one of the most significant land deals in history, the United States bought the Louisiana Territory from France for $15 million in 1803. This acquisition doubled the size of the young nation, adding about 827,000 square miles and securing control of the Mississippi River and vast tracts of land that now comprise multiple states, including Arkansas, Missouri, Iowa, and parts of Minnesota and Nebraska.

Following the Mexican–American War, Mexico transferred roughly 529,000 square miles of territory under the Treaty of Guadalupe Hidalgo. This treaty of Guadalupe Hidalgo was signed on February 2, 1848, that ended the war between the United States and Mexico. By its terms, Mexico ceded 55 percent of its territory, including the present-day states California, Nevada, Utah, New Mexico, most of Arizona and Colorado, and parts of Oklahoma, Kansas, and Wyoming. Mexico also relinquished all claims to Texas, and recognized the Rio Grande as the southern boundary with the United States.

The United States purchased Alaska from Russia for $7.2 million in 1867. Although initially criticised as ‘Seward’s Folly’, this acquisition by the US secured about 591,000 square miles of strategic northern territory that proved vital for resources and military positioning.

In 1917, the United States paid Denmark $25 million in gold coins for the Danish West Indies, today famously known as the US Virgin Islands. At the time, the islands’ position in the Caribbean was valued for naval strategy and to protect approaches to the Panama Canal.

The United States acquired Florida from Spain in 1819 under the Adams–Onís Treaty. While Spain received no direct payment, the US agreed to assume $5 million in claims for damages caused by American citizens who had rebelled against Spanish rule. Later, through the Gadsden Purchase of 1854, the United States paid Mexico $10 million for a 29,670‑square‑mile tract that became part of Arizona and New Mexico, facilitating the construction of a southern transcontinental route.

Although not strictly 'purchases', territories like Puerto Rico and Guam came under US control following the Spanish–American War. These acquisitions, while war‑related, expanded US influence significantly in the Caribbean and Pacific.