After the War of 1812, the U.S. began to focus on the building of the nation.
By 1815 several industries in the U.S. began to take shape and grow exponentially. Cotton was an important cash crop that was seeing a surge thanks to the the invention of the Cotton Gin a decade earlier. Our shipping industry, now free from British and French interferrance, was finally begining to thrive again, and industrial sites along the rivers of the northern states were beginning to turn out manufactured goods at a faster and faster rate.
We also continued expanding west. New states began seeking admission to the U.S. The defeat of Tecumseh spelled the end to organized Native resistance, and more and more families moved west. With this influx of new states came real poltical reforms which began including more common Americans into the political process. Andrew Jackson came to prominance as did his new Democratic party, which in 1828 succeeded in driving "the rascals" out of the White House.
Out national identity began forming. The first works of American literature, art and music appeared. Frontier tales and artwork began being admired by Europeans, something that never happened before.
It was a time of growth, both as a country and as a nation. I'd go with that to tie your paper together.