Looking at dates of admission in the South, I take back my previous idea. Mississippi and Alabama are admitted into the union ~8 years earlier.
So, I'm still going to use Napoleon as the catalyst for the POD, but this time it is during the Italian campaigns. Napoleon is able to defeat the Austrian forces at Caldiero, and drives on to Rome. Although he does not wish to, Napoleon deposes the Pope as requested by the Directory. He secretly allows the Pope to escape to the Kingdom of Naples. Sending men in pursuit they confront a small army sent by Ferdinand IV, this causes Napoleon to come into conflict with the Kingdom of Naples earlier. He sets up a government similar to Parthenopaean Republic, but this time based on land ownership in order to connect it to the people.
With Napoleon in the south of Italy, the Austrians begin to move again. With his southern campaigns finished Napoleon moves to confront the Austrians again. Fearing absorption by the Austrians, the Venetians offer Napoleon passage through their lands for their continued independence (Which would be in name only since the French would garrison Venice later on.).
To keep the army fed and armed, Napoleon and the Directorate, offer to sell Louisiana to the USA for 9,000,000 in cash (1802). The US takes it.
Napoleon still puts his brother Joseph on the Spanish throne causing the subsequent rebellion in the colonies and the creation of the Empire of Mexico.
Later, following Wolfhound's suggestion, the US pushes for 54-40 and gets more than they expected with the help of Russia.