So what exactly happened Tuesday night? Suddenly former Pennsylvania Sen. Rick Santorum has reemerged from the pack to claim the spotlight with three wins – Colorado, Minnesota and Missouri – while front-runner Mitt Romney is combing through the wreckage.

The former Massachusetts governor is arguing that last night was ultimately just a bump in the road to the nomination. No delegates were committed and he did not campaign hard in the states that held contests.

Still, three losses in one night was tough for Romney, a blow to his momentum at the very least. And as bad as the Tuesday results were at the state level for Mr. Romney, they were actually worse in some ways when you break the votes down to the county-level using Patchwork Nation.

Romney’s Bad Night

Romney did not win a single county in Minnesota or Missouri. He won 16 counties in Colorado, but there was a definite pattern to his wins and it centered on income.

The average median household income in the 16 counties Romney won in Colorado was about $59,600 in 2010. The media household income for the state in 2010 was $54,400. If you look at the dark green on the map below you will get a good sense of which counties Romney won – nearly of them are in that dark green area.

This map shows the counties Romney and Santorum won. We noted this wealth-divide pattern for Romney in Florida last week and noted the problems it could cause him in the future.

Romney did manage to win the wealthy suburban Monied Burb counties around Denver – places like Jefferson and Douglas counties – and Denver itself. And he won a string of counties in the northwest of the state. But he didn’t win them by enough to beat back Mr. Santorum’s wins everywhere else.

In fact, Romney didn’t win the Monied Burbs in Colorado overall – Santorum edged him 40 percent to 37 percent. And perhaps most troubling for Romney, he didn’t win any of the Monied Burbs counties in Missouri or Minnesota. The Burbs have given him his biggest support so far in this 2012 campaign and he struggled with them outside of Colorado on Tuesday.

In other bad news for Romney, he did not win Immigration Nation counties, places with large numbers of Latinos, that voted last night. He won those counties in Florida, thanks to Miami-Dade but last night Immigration Nation counties went to Santorum in Colorado and Minnesota on the whole – and by large margins overall.

If there was a bright spot for Romney it was that he at least managed to win Colorado’s Boom Town counties. That may prove significant in later primaries out west, but it’s not much of a consolation prize right now.

Santorum’s Strengths

Santorum, meanwhile, did well in all kind of counties on Tuesday. But his biggest strengths came in some key county types. He won the Evangelical Epicenters (57 percent of their vote in Missouri and 76 percent in Minnesota), the Immigration Nation counties, the small town Service Worker Centers and the aging Emptying Nests.

Those last two types, the Service Workers and Nests, may be especially critical in the coming weeks. Look at the map of Michigan below and note all the red (Service Worker Centers) and light green (Emptying Nests). Those places tend be both more conservative than other places and less wealthy.

Does Santorum’s win in those places in other states mean he is all set for Michigan? Hardly. Romney has a lot of advantages in Michigan, where his father was governor from 1963 to 1969. But Santorum’s appeal with voters in those places coupled with his strong pro-manufacturing message could play well in Michigan.

And as the primary schedule moves south those Evangelical Epicenters loom large in places like Georgia, Oklahoma and Tennessee.

So what exactly happened on Tuesday night? Time will tell for certain, but at the very least the Republican presidential contest got a lot more intriguing.