New York City approved exit signs meet UL, NFPA, and NEMA building and fire codes. The lettering for New York approved exit signs must have a one inch stroke and be eight inches high. The LED's on the New York approved exit signs must be red and the housing must be made of steel or aluminum.
The City of Chicago requires that any exit sign must be a rectangular 20 gauge sheet metal box with a glass or plastic face. Signs must be red lettering on white. The letters and arrows of exit signs and exit sign/emergency light combos are MANDATED to be red.