As the fight for a higher minimum wage continues across the country, a big part of the argument for higher wages concerns the cost of living—and how the wage needed to cover the costs of living fluctuates with geography. It is not a coincidence that the biggest battlegrounds in the Fight for 15 movement have been big cities, where everything simply costs more.

Amy Glasmeier, a professor of economic geography at MIT, developed the Living Wage Calculator to compare the cost of living with the minimum wage across the U.S. The idea came to her when she was studying impoverished communities. “We noticed that counties in poor regions had left poverty in the 1990s and then descended again into poverty,” Glasmeier told me. “We searched for the reason why and found that a lot of former poor counties that climbed out of poverty fell back in because they lost major employers. We knew that costs would not fall as fast and hence the tool was built to look at living costs.”

Glasmeier says that firms can use it to estimate how to pay their employees fairly, while workers can use it to see how high the cost of living is when considering moving to take a new job, or just as information about their home area. She made the map with the help of Allen Carroll, who works at the mapping technology company Esri, led the effort to built the interactive version of the map above.