Several communities around the state are having conversations about mergers between municipalities, ranging from Onekama Village and Township (total population < 1,000) to Grand Rapids & Kent County, which, as a single municipality of 606,000 people, would be the 24th largest city in the United States, right between Seattle and Washington, DC. No time to process right now, but some assorted links...

One Kent:

http://www.mlive.com/news/grand-rapids/index.ssf/2011/03/one_kents_new_city-county_gove.html