What new political developments emerged out of the American Revolution?
The major political development that emerged from the American Revolution was the creation of the first major republic in modern times. This was a republic with a written constitution and, once the Constitution was written, a system of separation of powers and checks and balances.
A few years after the Revolution was officially ended in 1783, the US wrote for itself a new Constitution. A nation that was formed as a republic, with a written constitution, and a system of government that was specifically meant to limit the government's ability to tyrannize the people was a new thing. This was an age of monarchy and of governments with very few limits. The United States that emerged from the Revolution was new because of its commitments to these ideas of limited government.