Amy Jennewein speaks during a rally in support of raising the minimum wage in University City, Mo., on April 25. (AP Photo/Jeff Roberson)

Raising the federal minimum wage to $10.10 would have widely varied impact on the nation’s congressional districts, according to a new report.

There is a more than fourfold gap between districts where the impact would be largest and smallest, according to the analysis by the progressive group Oxfam America (data mapped below). The group advocates for the increase, which is also supported by President Obama. Disagree with the math — the data underlying the analysis have their limits, which we’ll get to in a bit — but at the least Oxfam’s analysis offers a relative picture of how dramatically different the effect would be by congressional district. 

On average, Oxfam found 19 percent of the workers in each of the nation’s 435 congressional districts would be affected by a $10.10 hike. Among the 25 districts where the impact would be most widespread, 17 are currently represented by Democrats, with the East Los Angeles area being home to the district where a hike would have the largest impact. There, in California’s 40th congressional district represented by Rep. Lucille Roybal-Allard (D), 31.8 percent of workers would be affected by a minimum wage hike, Oxfam found. The increase would affect the smallest share of workers — 6.8 percent — in New York’s 12th congressional district, represented by Democrat Carolyn B. Maloney.

But, overall, there isn’t much difference between districts represented by either party, the report finds. On average, Democrat-represented districts would see 18.7 percent of workers affected by a hike, while Republican-represented districts would see 19.8 percent of workers affected. The districts with the highest share of potentially affected workers range from urban to rural areas—the top district is urban, the next is rural. The districts with the lowest rates are all urban and parts of Los Angeles, San Francisco and New York City are featured both in the top and bottom 10.

The research was conducted by the economist David Cooper, an analyst who also works for the progressive Economic Policy Institute. The methodology is laid out in great detail here, but basically he crunched the numbers in a few steps:

  1. Cooper started with very local granular data collected by the Census Bureau.
  2. Then, he used an academic matchmaking program to map that local area data to congressional districts.
  3. Finally, he calculated hourly wages using the annual incomes, weeks worked per year and hours worked per week.

Anyone earning between $7 and $11.50 was determined to be affected by the minimum wage hike. Why $11.50 and not $10.10? As the Congressional Budget Office noted in its estimates earlier this year, there’s a ripple effect. If a worker makes $9 and his boss makes $11.25, a new federal minimum wage of $10.10 could force both of them to get a raise to maintain a company’s pay ladder.

Cooper’s analysis yields results similar to CBO’s at a national level. The CBO estimates 24.5 million would be affected by the wage hike, he finds 25.1 million. (CBO also estimated that 500,000 people would lose jobs if the minimum wage is increased to $10.10, which the Oxfam report does not seem to factor in.) Cooper’s methods may make sense, but the underlying data are limited and several assumptions were made. The Oxfam report itself confirms those limitations in explaining the research methodology:

[T]he margin of error for the data used in the map is large enough that differences of a few tenths of a percentage point may not be statistically significant. The rankings give a general sense of which districts have a higher percentage of workers who would benefit from a $10.10 minimum wage. For example, we would rank, in order, districts with 27.0 percent, 26.7 percent, and 26.4 percent of workers who would see a benefit from an increase; however, the differences may be negligible.

All that is to say, the report isn’t definitive. Even if it overstates the impact of a minimum-wage hike, it serves as a rough guide to how the impact of a wage hike would affect each congressional district differently. The map below shows that impact, at least according to the Oxfam analysis. Darker shades represent a larger share of workers affected.

Click here to view a larger version of the map.