How did the united states change between 1776 and 1870?

The united states changed in many ways. population in 1770  was  2,148,100. population in 1870 was 38,558,371 the very most important event was the american civil war. the civil war was  from 1861-1865. this started  the 14th Amendment which defined a citizen. it said as "any person born or naturalized in the us." the 13th amendment abolished slavery, and the 15th amendment prohibits denying the right to vote to someone because of their race. other  events include the louisiana purchase, the texas revolution, the spanish-american war, the war of 1812, the purchase of alaska, the mexican cession, the indian wars, and the california gold rush.the right to vote was extended to all male citizens by the 15th amendment. women were not given the right to vote until the 19th amendment was passed in 1920.