How was america in 1790 different from america in 1820?

This was an example of Alexander Hamilton's genius. The significance of the national bank was it made the repaying of the debt much easier and forced everyone to use the same currency.

Eli Whitney invents Cotton Gin. The cotton gin made the cotton industry of the south explode. Before the cotton gin, separating the cotton from its bowl took to long, making it unprofitable. However, after Eli Whitney unveiled the cotton gin, processing cotton became much easier resulting in greater availability and cheaper cloth. The invention also had the by-product of increasing the number of slaves needed to pick the cotton, indirectly strengthening the arguments for continuing slavery.

The tie in the Electoral congress was significant because the aftermath of the Election of 1800 resulted in the passage of the 12th amendment in 1804 requiring that electors vote specifically for the offices of President and Vice President. This election proved that the United States could survive the exchange of power between opposing parties when the Democratic-Republicans took over after the Federalists had been in charge.

Marshall dominated the Court for over three decades and played a significant role in the development of the American legal system. His biggest achievement was that he reinforced that federal courts can use judicial review, by disregarding laws if they are deemed unconstitutional.

Thomas Jefferson purchases nearly 830,000 square miles from French leader Napoleon Bonaparte. This is significant because it doubled the size of The United States. It also set the precedent for purchase of foreign lands.

Marbury v. Madison was one of the defining cases of the U.S. Supreme Court. Marbury was a man who was appointed immediately before Madison took office. Madison replaced him with one of his own appointees when he took office, and Marbury sued, claiming he could not be removed under the terms of the Constitution. Madison claimed that as president, he had the right to interpret the Constitution. The significance of this was that the Supreme Court found that the executive branch had no such rights, interpretation of the Constitution was strictly reserved for the Supreme Court.

Robert Fulton invented the steam boat. The steamboat was the first mechanically powered vessel known to mankind. 
It made ‘up stream" passage of the Mississippi possible, thus making the Louisiana Purchase lands much more accessible.

Slave trade was ended. This was significant because it was the first step towards abolishing slavery. Slaves were no longer allowed to be imported to another country.

War of 1812 begins.The War of 1812 was, in a sense, the Second War for Independence. By defeating the strongest nation in the world for the second time, the U.S. proved that it had a right to exist, a right to be its own country, and a right to be a world power.

Missouri Compromise-The Missouri compromise admitted Maine to the U.S. as a free state, while admitting Missouri as a slave state. It set the precedent for slave vs. non-slave states. This preserved the balance of free and slave states in the U.S. Senate, but it extended slavery west of the Mississippi River.

the answer is mass marketing.