“These are men who were keeping us competitive when everyone else was disinvesting,” said Ralph A. Lange, the city manager in Ypsilanti. “For those of us on the ground level, if not for them, we wouldn’t have half of what we’ve got.”

With the retirement of Mr. Levin, Mr. Dingell and Mr. Rogers, as well as Representative Dave Camp, a Republican, Michigan will lose four of its most senior members, and all the firepower that came with them. This comes on the heels of Michigan’s decade-long population slide, which cost the state a seat after the 2010 census.

In many ways, the retirement of the four is symbolic of the huge shifts in how Congress functions. The combination of a ban on earmarks, which once enabled members to help their communities, and the rabid partisan rancor of late, which was far less prevalent through most of the careers of the four men, gives their departure a sense of an ending era.

Further, this depletion has civic leaders, business owners and residents deeply worried about the loss of advocacy and the end of a rare bipartisan force for good.