It may seem like there are "missing" cities, but there are not. For instance, Pittsburgh doesn't appear because it is smaller than Cleveland. But Cleveland also doesn't appear because it is smaller than Detroit. So a large blank space is created.
The "glitch" may be that Texan bigger cities are quite alone, but in the northeast they are closer together.
There may be more but these were he ones i found.
Source: I used wikipedias list of cities in Alaska and checked it on Google Maps.