A discovery of an item called "Chicago Fried Chow Mein" on a 1946 Los Angeles Chinese restaurant menu launched a thread on the General Topics Board which created a lot of speculation, but not a lot of information. Some felt it was characterized by the use of deep-fried noodles, others that it was characterized by the brown sauce used.
A cursory Googling found that this creation still can be found in parts of New England, especially in the smaller cities in MA and RI (i.e., not Boston or Prividence). There's also someindication that it may be more common in Polynesian or Tiki-themed Chinese restaurants.
Can you find "Chicago" Chow Mein on menus in your community, and if so, where are you? What characterizes it, in your mind?