I’ll be adding more maps interpreting the Michigan primary over the next day or two, but here’s a simple one to start with, showing which candidate got the most votes from the combined Democratic and Republican contests in each county. (In Ann Arbor’s Washtenaw County, the “uncommitted” vote on the Democratic side came out on top.) The five counties that cast the most votes in the 2004 general election are labeled by name.

If John McCain does not get the Republican nomination, those green counties could be important in November. But Macomb and Oakland counties, in suburban Detroit, are almost always crucial in close presidential elections: In 2004, George W. Bush won the former by only 6,000 votes and lost the latter by 2,000 votes.