The Louisiana Purchase, which was actually made by Jefferson himself, was a shift in his general principles because it required great power on behalf of the federal government, which Jefferson himself didn't like. The same goes for the Monroe Doctrine.
This should be the neutrality act of 1939, also known as the cash-and-carry
I'm not sure if any were begun in 1775. The American Revolution was occurring at the time but it started in 1760's the sugar and stamp acts were in 1764 and 1765, While the Townsend act was in 1770. The declaration wasn't even started until 1817.
Parthenon I believe.... that's what I last remember
The annexation of Texas, a slave state, raised a lot of tension because it ruined the balance of power between the North free states and the South slave states.
