what caused the areas of the united states to nearly double between 1800 and 1810
Economic history of the United States Although there was relatively little immigration from Europe, the rapid expansion of settlements to the West, and the Louisiana Purchase of 1803, opened up vast frontier lands. The high birth rate, and the availability of cheap land caused the rapid expansion of population. The average age was under 20, with children everywhere. The population grew from 5.3 million people in 1800, living on 865,000 square miles of land to 9.6 million in 1820 on 1,749,000 square miles. By 1840, the population had reached 17,069,000 on the same land.[68]
Mexican–American War Before the secession of Texas, Mexico comprised almost 1,700,000 sq mi (4,400,000 km2), but by 1849 it was just under 800,000 square miles (2,100,000 km2). Another 30,000 square miles (78,000 km2) were sold to the U.S. in the Gadsden Purchase of 1853, so the total reduction of Mexican territory was more than 55%, or 900,000 square miles (2,300,000 km2).[166]