The movie about infamous bank robber John Dillinger and his associates is to open July 1.
The Chicago Sun-Times said Graham Thompson and his Optimo Hats establishment created about 75 hats, mostly fedoras, for "Enemies."
"Our business makes hats that are of the quality of the 'great hats' of the 1930s and 1940s," Thompson told the newspaper.
The milliner went on to say the movie's director, Michael Mann, and costume designer, Colleen Atwood, were dedicated to making sure the clothing and hats the actors wore were faithful to the era.
Thompson, who previously made headwear for the movies "Cinderella Man," "Road to Perdition" and "The Lost City," said "Enemies" was "the first one where the hats are spectacular."
"The designers really nailed the '30s," he said. "The hats are right."