Located in the Eastern (GMT -05:00) time zone. Area code 734 serves the state of Michigan. This area code was assigned on May 30th, 1997. On December 13th, 1997 it went into service. 734 is a General Purpose Code. 734 service area does overlap with 313 area codes. Dialing pattern for local calls within the same NPA (area code) is 7D.