2.Westward Movement

In the 18th and 19th centuries，the US frontiers extended westward step by step.For the sake of convenience，this westward expansion may be treated in three stages：the settlement of the region between the old seaboard states and the Mississippi River；the settlement of the Louisiana Territory；and the occupation of the far southwest.The occupation of the territory east of the Mississippi can be gleaned from the following table showing the dates on which states were admitted to the Union.

Admission to Union

1792—Kentucky 1796—Tennessee

1803—Ohio　　　　　　1816—Indiana　

1817—Mississippi　　 1818—Illinois

1819—Alabama　　　　 1837—Michigan

1845—Florida　　　　 1848—Wisconsin

In the meantime expansion beyond the Mississippi was under way.The inhabitants in the region of the Louisiana Purchase were very complicated.The great majority of dwellers were the descendants of the French pioneers who had long before settled at important trading centers，particularly at St.Louis and New Orleans.Others were Spanish residents，who had moved up from Spanish territories or from Spain itself.Here and there were also Americans who had crossed the Mississippi even while the west bank was under a foreign flag.At the extreme western end of the Louisiana Purchase，fur traders，missionaries，and farmers from the East were expecting the settlement of the Oregon Territory between Britain and the US.In 1846 Britain agreed to give up its claims on this land，and the Oregon boundary on the north was fixed at the forty-ninth parallel.South of the Oregon Territory other Americans were settling a large tract of land that belonged to Spanish Mexico.The southwest as a whole was sparsely settled in the early years of the 19th century.Excluding the Indians，the inhabitants there were chiefly Mexicans or Spanish.By 1834，the US citizens outnumbered the Mexicans in Texas.In 1836Americans revolted.Texas then became an independent country that was called the Lone Star Republic.The Republic lasted nine years，and in 1845the United States annexed Texas and made it the twenty-eighth state of the Union.At the same time，many Americans were settling in California and other lands in the southwest.In 1846the United States declared war on Mexico.The war lasted two years.In 1848Mexico and the United States signed an agreement.The Rio Grande became the border between Texas and Mexico.And what are now the states of California，New Mexico and Arizona was ceded to the United States.The US mainland as we know today was almost complete in 1848.

Ceded Territories from Mexico