The federal minimum wage has been stuck at $7.25 for 13 years, despite attempts to raise it.
The National Employment Law Project analyzed the impact of local hikes to the minimum wage since 2012.
That year marked the first action by Fight for 15, a worker movement calling for a $15 minimum wage.
But those disparities among workers in states with a higher minimum wage versus those in states still adhering to the federal minimum wage means that workers in the South are left behind, according to Lathrop.
In Washington, DC the minimum wage is $16.10 an hour, but five states — Alabama, Louisiana, Mississippi, South Carolina and Tennessee — have no minimum wage, defaulting to the federal minimum.