Anyone who pays even passing attention to politics knows that the November presidential election will be a referendum on the nation’s economy.

And, anyone who pays even passing attention to Fix — we assume that’s virtually everyone in the country, right? — knows that for the average voter the health of the economy is largely determined by the unemployment rate both nationally and in their particular state.

Given the primacy of the unemployment rate in peoples’ perception of the state of the economy — and, consequently, on their votes — we are forever in search of data to illustrate which way the trend line on the economy is headed.

That’s where Patchwork Nation — an amazing mapping and demographic project run by Fix friend Dante Chinni — comes in. We asked Dante to produce a few maps charting the unemployment rate over time both nationally and in the Rust Belt (Ohio, Michigan, Pennsylvania and Wisconsin).

The four maps below tell the story of the 2012 election — or at least a major part of it. They suggest that Obama can make the case that the trend line on the economy is moving in the right direction — both nationally and in a key region of the upper Midwest that could well decide who wins in November.

Obviously, events can intercede; early predictions on April’s jobs report don’t look promising for the White House. But, these four maps do tell a positive story — if not as positive a story as they’d like — for the Obama Administration on the economy.

Map #1 is a look at where the unemployment rate stood nationally in January 2009 when President Obama took office (the more red, the higher the unemployment rate; the more white, the lower the unemployment rate):

Map #2 is the unemployment rate nationally as of March 2012:

Map #3 is the unemployment rate in the Rust Belt in January 2009:

Map #4 is the unemployment rate in the Rust Belt in March 2012: