Rhyming ”Decatur” with ”alligator” is clever. Writing a whole album about people and places in Illinois, the second in a projected series of albums about all 50 states, threatens to be insufferably gimmicky. It’s not. ”Sufjan Stevens invites you to: Come on feel the Illinoise” (Asthmatic Kitty) creates a kind of psychohistory via Americana in songs that metamorphose from wistful to grand, from historical character study to private reminiscence, from banjo to orchestra, from minimalism to fuzz-toned rock. Even the most elaborate constructions come across as homemade, touched with an optimism that is by no means naive.