A year after he graduated, Lahti opened a State Farm Insurance agency in Hancock.
Lahti was a small business owner and real-estate developer, owning private and commercial lands all across the Keweenaw Peninsula.
In 2006 he announced his intention to run for the State House seat District 110, being vacated by Democrat Rich Brown.
Lahti easily won the Democratic Primary, and went on to face Republican Dave Schmidt in the General Election.
In 2010 Lahti ran for the Michigan Senate in the 38th district, which includes the western Upper Peninsula.