The Kingdom of Florida declared independence on May 1st 1943 after the loss of the Imperialist Compact, of which Spain was a member, in the Eurasian War. While Florida and Puerto Rico, the two overseas possesions of Spain in the Americas, barely saw any fighting, both colonies reacted differently to the war. Anti-war sentiment dominated Puerto Rico, while Florida was filled with patriotic fervor. When Madrid fell to Anglo-French forces and both Danubia and Russia were exhausted from seven years of warfare, the Peace of Geneva was signed in 1943. Spain lost their few remaining colonies in Asia and Africa to the victorious Alliance of Nations and the fate of both Puerto Rico and Florida was up in the air. The island of Puerto Rico, supported by strong republican nations like Mexico, Cuba, and Venezuela, chose independence from Spain and a constitution modelled after the Cuban one. Florida initially wanted to remain with Spain, but the suprise vote in the Spanish parliament which led to the abolishing of the monarchy changed that. Floridian monarchists declared independence from Spain and invited the deposed royal family to come to North America. Infante Jamie Alfonso and his young wife, the Habsburg princess Luisa Sofía, came to San Agustin to become King and Queen of Florida.
Florida is the only monarchy of North America not ruled by the British monarch, and since the 1992 Constitutional Referendum in Brazil the only monarchy in Latin America. Florida has three neighbors, the Republic of Georgia (the southernmost nation which replaced the Thirteen Colonies), the Commonwealth of the Bahamas, and the Republic of Cuba. Relations with Cuba, while initially frosty, have thawed in the last thirty years. Georgia, which for the longest time had negative relations with the Spanish Empire due to Spanish support for the Seminole, have been cordial since Florida's declaration of independence.
Also please excuse any language mistakes, because I don't speak Spanish.
EDIT: Slightly improved the Spanish and had to use a different paper texture because oh genius me deleted the one I originally used already.