Copyright Civis Analytics, 2013

Political strategists running a presidential campaign see a different map of the United States than the rest of us. To reach the voters who will decide an election, those strategists often have to buy advertisements across state lines. Reaching voters in rural Nevada means buying ads in Salt Lake City; swaying votes in northern Wisconsin means purchasing television time in Duluth, Minn.

Now, for the first time, one of the biggest ad buying firms in the country has crunched the data to show where President Obama and Mitt Romney won, by media market. And the results are surprising.

President Obama’s best media market wasn’t in a liberal enclave like San Francisco or Portland, but in tiny Laredo, Tex. Obama beat Romney by 54 points along that stretch of the U.S.-Mexico border. And Romney did best in northern Texas, in the Abilene-Sweetwater market, where he beat Obama by 60 points.

Check out this map of U.S. media markets, broken down by the Democratic media firm GMMB and Civis Analytics. The Obama-Romney Difference in Vote tab will give you results of the 2012 elections:

(Source: Civis Analytics)

Explore the rest of the tabs, and you’ll see why Obama did so well along the border. More than 90 percent of voters in Laredo are Hispanic, a group among whom Obama did particularly well.

The map also gives a good sense of where the Affordable Care Act will have the biggest impact. Click the Percent Uninsured tab to see just how many people are uninsured along the border and in rural media markets throughout the West. In large swaths of Idaho, Montana, California and Oregon, along with huge parts of the South, more than 20 percent of the population remains uninsured.

But that doesn’t equate to support for the president: In media markets like Bluefield, W.Va., the Tri-Cities on the Tennessee-Virginia border and Knoxville, where more than one in five residents is uninsured, Romney won by more than 40 points.

Opponents of Obamacare have been focusing their advertising dollars on media markets with the highest level of uninsured Americans, in hopes of undermining the law’s success. Our colleague Sean Sullivan reported on the ad spending here, thanks to Kantar Media Intelligence estimates.