The seceded southeastern part of the former USA, Imperial Americana encompasses mostly what was once Texas, Louisiana, and Georgia, as well as parts of the Midwest . As its name suggests, the country is led by what appears to be a largely monarchist political administration, though its rumoured that some kind of an elected congress still exists as well .
A militarized, and to some extent, extremist state, Imperial Americana has a long history of chafing against the other federal American remnant, known generically as the US-Soviet Alliance , as well as other socially progressive nation-states in the world like Poseidon, and especially Olympus. Their reactionary, and often militaristic approach to world politics seems to be a sore point for many peacekeeping and diplomatic ventures.
Technologically speaking, Imperial Americana strikes a balance between old-school but high-quality, at least in the sector of armaments. In Appleseed Hypernotes, ES.W.A.T. intercepts an ocean freighter smuggling a motley variety of weapons and munitions, bound for Lisbon, Spain, following a stopover in the Kitasuiten Province of Olympus . Amongst the modern products of Poseidon, such as vibra-cutters (seen in action in both Hypernotes and the 2004 movie) are a range of suppressive fire weapons that bear the markings of Imperial American factories. As such, the state appears to still favour bullet and projectile-based weapons, similar to Olympus, but unlike Poseidon, which (besides owned company Seburo), seems to be leaning towards laser and vibration based armaments.
Appleseed and Ghost in the Shell
A similar country called the American Empire appears in the world of Shirow Masamune's Ghost in the Shell, and could be considered a predecessor to Imperial Americana. For more information, check out the American Empire page on the Ghost in the Shell Wiki.
 Appleseed ID encyclopedia, page 26.
 Appleseed ID encyclopedia, page 119.
 Appleseed Hypernotes, page 54