Demonstrators outside a National Restaurant Association conference in Washington on April 29, 2014. (Alex Wong/Getty Images)

The March 30 editorial “Raise the minimum wage — the right way” called for a regional minimum wage. We’ve seen this idea before. When Congress first debated a national minimum wage in the 1930s, segregationist Democrats in the South fought for different wages based on race. A compromise, ultimately deemed unconstitutional, allowed regional and occupational variations that in practice maintained the same racial disparities.

Even the law that eventually established the federal minimum wage included carve-outs for jobs largely filled by black workers: farm work and domestic work. A regional wage would exacerbate existing racial and geographic disparities that have kept millions of workers behind for decades. There’s nowhere in the country where a worker can support a family on $15 an hour. So why should workers in the South and elsewhere be left behind?

Half of black workers across the country live in states where the minimum wage has stayed at or below $7.25 an hour, most concentrated in the South. And, ironically, while a regional wage would harm black workers, especially black women, the worst, it would end up hurting workers of all colors by keeping a decent wage floor perpetually out of reach.

William Barber II, Goldsboro, N.C.

The writer is president of Repairers of the Breach and co-chair of the Poor People’s Campaign: A National Call for Moral Revival.

Mary Kay Henry, Washington

The writer is president of Service Employees International Union.