The map on this page shows not only who’s winning in each of the state’s 83 counties, but, using Patchwork Nation, it shows how the candidates are doing in each of Michigan's nine  types of county – from the wealthy Monied Burbs to the Service Worker Center counties. It will fill in with data as the results from the primary comes in.

What to watch for:

There are two primaries Tuesday, but the majority of the attention is going to be on the Michigan primary where former Massachusetts Gov. Mitt Romney has surprisingly found himself in a real fight with former Pennsylvania Sen. Rock Santorum.

Arizona also holds a contest, but the ballots have been streaming in for weeks there under that state’s rules and based on polling the belief is Romney has an insurmountable lead.

Michigan, however, is Romney’s “home state” – or at least where he was born – and it was assumed it would be safe territory for him. He won Michigan in 2008, beating Sen. John McCain by 9 percentage points.

That was a long time ago and Romney is in a very different campaign now.

First, in 2008 Romney ran as the conservative alternative to McCain, that is territory Santorum has staked out this time. Second, in a time of economic hardship, Romney has been painted as the wealthy, out-of-touch businessman – an image he has reinforced with numerous gaffes in the last few weeks. And third, while none of the GOP candidates endorsed the auto bailout that arguably saved this state, Romney may pay a special price for his famous “Let Detroit Go Bankrupt” Op/Ed. Because he is a son of the auto industry (literally, his dad was head of American Motors), some here have taken special offense.

What does that all mean for Tuesday night? There are three areas to watch.

1. Watch the tri-county area around Detroit in the southeast corner of the state – Wayne, Oakland and Macomb counties. They are the main population center and provided more than 40 percent of Romney’s votes in the 2008 primary.

Macomb and Oakland are Monied Burbs using Patchwork Nation’s demographic/geographic breakdown and the Burbs have been good for Romney in primaries and caucuses so far. But pay especially close attention to Macomb, which is not quite as wealthy and is home to more blue-collar voters. Romney has struggled with blue-collar voters in other states. If he loses Macomb he’s probably in trouble.

And in a broader sense watch the vote total coming out of those three counties. In 2008 Wayne, Oakland and Macomb contributed 99,000, 133,000 and 77,000 votes respectively. If those numbers are down a lot it may mean the GOP has real problems in Michigan with its stance on the auto bailout.

2. Genesee County, just north of Oakland, is home to Flint Michigan, which has been ravaged over the last 30 years by the problems in the auto industry. But Genesee, which is a Minority Central county in Patchwork Nation, has something else many of those counties tend to have – a strong social conservative bent among the white voters there. Santorum spent a good chunk of Sunday in Genesee. If you see the county go from Santorum, that is a good sign for him.

3. Michigan’s north is home to many small town Service Worker Center counties and those places, which have much smaller populations offer an interesting test for Santorum Tuesday night. The lower incomes and education levels in these counties should push them toward Santorum, but they are usually not heavily socially conservative. These places, in other words, are good for Santorum’s blue-collar appeal. The question is whether Santorum’s cultural conservative rhetoric may have pushed voters in them away.