Woe to the Europa player who ever would have to create maps for the US coast and put CD counters on them in any Europa scenario. Any game in which the Axis would be able to mount a significant threat to the US is one that has already turned sour for the Allies.
If you should find in such a predicament, though, the first and best source for such information would be the Coastal Defense Study Group and its exhaustive Wiki covering the history of US fortifications. The CDSG works to educate and preserve the history of the United States coastal defenses, and does so through conferences, a journal, and the already mentioned resources on the web.

URL: cdsg.org