Notice the heading is nationalities, as in citizens of a nation.
Nationalities, etc. 5.22. The table on Demonyms in Chapter 17 ``Useful Tables'' shows forms to be used for nouns and adjectives denoting nationality. 5.23. In designating the natives of the States, the following forms will be used. Alabamian Louisianian Ohioan Alaskan Mainer Oklahoman Arizonan Marylander Oregonian Arkansan Massachusettsan Pennsylvanian Californian Michiganian Rhode Islander Coloradan Minnesotan South Carolinian Connecticuter Mississippian South Dakotan Delawarean Missourian Tennessean Floridian Montanan Texan Georgian Nebraskan Utahn Hawaiian Nevadan Vermonter Idahoan New Hampshirite Virginian Illinoisan New Jerseyan Washingtonian Indianian New Mexican West Virginian Iowan New Yorker Wisconsinite Kansan North Carolinian Wyomingite Kentuckian North Dakotan From:
[U.S. Government Printing Office Style Manual] [Chapter 5 - Spelling]