What is the american expanison?

The second half
of American expansion is the imperial era of the United States, starting with the
Spanish-American War in 1898 and continuing, some would argue, until today.  After the 1899
Treaty of Paris ending that conflict, the US came into possession of Puerto Rico, Guam and the
Philippines, as they were formerly Spanish colonies.  This was the birth of the American
Empire.

Its growth continued as Roosevelt declared the Carribbean Sea an
"American lake" in the Roosevelt Corollary, and in the years following, the
US...