Within filly years the United States grew from a relatively small republic centering on the Atlantic seaboard to a continental power. The process of territorial growth was started by Jefferson. The purchase of Louisiana almost doubled the original area of the United States. The process was furthered by the occupation of West Florida and by the acquisition of Florida in 1819.
In the meantime the boundary between Canada and the United States was Fixed at the 49th parallel, thus settling the question of the northern limits of the Louisiana Purchase. The Maine boundary was satisfactorily adjusted in the Webster-Ashburton Treaty of 1842 from that year the United States held a clear title to all the land from the Gulf of Mexico to the Great Lakes, and from the Atlantic Ocean to the western boundary of the Louisiana Purchase.
The process of expansion continued Americans had moved into Texas in considerable numbers. They rapidly developed resentments against Mexican control. In a swift war, marked by the tragic loss of the Alamo and the brilliant victory at San Jacinto, the Texans won their independence. The Republic of Texas was beset by dangers. It asked for union with the United States. Alter prolonged debate Congress annexed the republic as the stale of Texas in 1845.
In the meantime. Americans had pushed into Oregon. The agreement with Great Britain provided for joint occupation, but the Americans clamored for undisputed possession. The government asserted our claims to the whole of Oregon, northward to the Russian Treaty line of 54° 40°. In a spirit of compromise, the government negotiated a new boundary line. The 49th parallel which was the boundary east of the Rocky Mountains was extended to the Pacific with the exception of Vancouver Island, all of which was ceded to Great Britain.
Then the dispute with Mexico resulted in war and new acquisitions. The annexation of Texas was recognized by Mexico. The Mexican Cession was subsequently divided into California, Utah, Arizona, and New Mexico, with portions being assigned to Wyoming and Colorado One last addition to the continental area of the United States was made in 1853 the Gadsden Purchase was negotiated in order to secure control of the Gila valley which provided a convenient route for a railroad to the Pacific
Thus the unsure republic of 1783 had become the continental nation of 1853.
Growth of the United States (1776-1853)
1776: Original Thirteen States & 1783-1802: Western Cessions – 888,811 square miles
1803: Louisiana Purchase – 827,192 sq.mi.
1810-1819: Florida (and other areas from Spain) – 72,003 sq. mi.
1845: Texas – 390,144 sq.mi.
1846: Oregon Country – 285,580 sq.mi.
1848: Mexican Cession – 529,017 sq.mi.
1853: Gadsden Purchase – 29,640 sq.mi.