The correct answer to this open question is the following.
Despite Thomas Jefferson’s goal of limited government, his administration doubled the size of the United States with the purchase of the Louisiana Territory. This led to a dispute between the U.S. and Spain over the borders of the territory.
The Louisiana Purchase was sealed in April 1803, when France accepted to sell the Louisiana Territory to the United States, for $11,250,000. After this, President Thomas Jefferson ordered the Lewis and Clark expedition that lasted to years of exploration of the newly acquired territories.
The territorial differences with the Spanish crown were resolved with the signing of the Adams-Onis Treaty of 1819. The agreement was that Spain ceded the Florida Peninsula to the United States and the establishment of a border of the US with the territories of the New Spain(later Mexico, due to its independence movement).