More than half of the modern United States arrived with a price tag. Here is what the country paid, and what "paid" actually meant.
The US map looks like the product of exploration and war, and much of it was. But a surprising share was the product of a transaction. On seven occasions between 1803 and 1917 the country bought land from another government, signed a treaty, and moved the border. Add them up and they account for more than half of the nation's present-day area, for a nominal 97 million dollars spread across 114 years.
The price per acre is the first thing that jumps out, and it jumps a long way.
Louisiana, the interior third of the country, went for about three cents an acre. Alaska for about two. At the other end sits the smallest deal of the seven, the Danish West Indies, now the US Virgin Islands: 134 square miles bought in 1917 for 25 million dollars in gold, nearly 300 dollars an acre. The United States was not buying land there. It was buying a naval position in the Caribbean in the middle of a world war, and it paid position prices.
Read the chart that way and the logic holds. Cheap land is empty and far away. Expensive land is small and strategic. What the buyer paid for was rarely the dirt. It was distance, timing, and leverage.
Every deal that moved the border, with what it cost, what it bought, and where it sat.
Three of the seven followed one script: a war was fought on the land, the seller lost, and a payment was written into the treaty that ended it. The Mexican Cession of 1848 handed over California and most of the Southwest for 15 million dollars, but only after the United States had already taken it and occupied Mexico City. The Gadsden strip followed five years later, sold by the same defeated government. In 1898, Spain took 20 million for the Philippines, a check stapled to the end of a war it had just lost.
Calling these purchases is technically accurate and practically misleading. The money was real. The choice was not. On the chart above, those three are drawn apart for exactly that reason.
Bought outright, the plain purchases come to about 39 percent of the country's area, most of it Louisiana and Alaska. The forced deals add roughly another 15, almost all the Mexican Cession. Together they clear half. The remaining 46 percent came by other means: the annexation of Texas and Hawaii, the treaty with Britain over the Oregon Country, and the original territory won in the Revolution. None carried a purchase price, so none appear here.
A majority of the United States, measured in land, was acquired through a deal with a dollar amount attached. Some of those dollars bought willing sellers. Some of them followed an army. The map does not distinguish between the two, which is the reason to do it deliberately.