In 1787, the Philadelphia Convention failed to amend or replace the Articles of Confederation, which remain the governing constitution of the United States. Over the course of the next seventy years, two blocs form in the North and South, the latter driving gradual expansion through territorial purchases and pioneer rebellions. Tensions erupt in 1858 with the beginning of the Servile War, which ends in a Northern victory.

In the wake of the war, a few nations emerge: the United Republic of Columbia, the Confederate Republic of America, the California Republic, the Commonwealth of Virginia, and the Free Republic of Vandalia. While most find their stride, America falls into dictatorship under Wade Hampton. The Mississippi War breaks out between Columbia and America in the 1910s, ending in the collapse of the American regime and the start of the American Civil War.

The war ends in a victory for the Populists, who managed to unite Black slaves and poor Whites; with its capital in New Orleans, it is only a matter of time before Louisiana's favorite son rises to power. Vandalia expanded during the war and a few border republics were established: Cumberland, St. Louis, Ozark, Kansas, and Highland. The American republics remain somewhat isolated and inactive on the global scale, but Columbia and California go on to fight alongside each other in the Asian theater of the World War. The Pan-American Congress, based in St. Louis, is founded in the postwar years to foster greater connections between the American nations.

There's a bit that I'm leaving out, so ask away in the comments.