Though the South is the region of the United States with the greatest concentration of income inequality, its representatives in Congress are doing a poor job of addressing the problem.

The Institute for Policy Studies released a report this week that grades federal lawmakers on 40 legislative actions over the past two years that either helped the most affluent or the poorest of their constituents. They ranged from a bill to establish a "Buffett Rule" minimum tax rate for wealthy Americans to legislation raising the minimum wage and indexing it to inflation.

Of the states with the most uneven income distribution, only one -- Massachusetts -- has senators and representatives who earned an overall average "A" score. The 13 Southern states* earned an average score of C-. Of those 13 states, 10 have among the highest income inequality index scores nationwide, according to a recent U.S. Census Bureau report.

"Members of Congress have the capacity to make sure all Americans, not just a privileged few, share in the wealth that we all together create," says study co-author Scott Klinger. "With this new report card, voters can see for themselves how well their elected lawmakers are meeting that responsibility."

Among the findings:

* Republicans make up the entire list of 11 senators who got an "F." They include John Boozman of Arkansas, Richard Burr of North Carolina, Saxby Chambliss of Georgia, Lindsey Graham of South Carolina and Johnny Isakson of Georgia.

* Republicans also make up the entire list of 48 representatives who got an "F." They include Sandy Adams of Florida, Marsha Blackburn of Tennessee, Kevin Brady of Texas, Mo Brooks of Alabama, Michael Conaway of Texas, Rick Crawford of Arkansas, Renee Elmers of North Carolina, John Fleming of Louisiana, Kay Granger of Texas, Tim Griffin of Arkansas, Sue Myrick of North Carolina, Rich Nugent of Florida, Alan Nunnelee of Mississippi, Pete Olson of Texas, Steven Palazzo of Mississippi, Bill Posey of Florida, Martha Roby of Alabama, Phil Roe of Tennessee, Dennis Ross of Florida, Steve Scalise of Louisiana, Austin Scott of Georgia, Tim Scott of South Carolina and Steve Womack of Arkansas.

* Three of the six Democratic senators most friendly to the interests of the 1% most affluent Americans are from the South: Kay Hagan of North Carolina, Mark Pryor of Arkansas and Jim Webb of Virginia.

* Six of the 11 most 1% friendly Democratic representatives are from the South: John Barrow of Georgia, Ben Chandler of Kentucky, Henry Cuellar of Texas, Larry Kissell of North Carolina, Mike McIntyre of North Carolina, and Mike Ross of Arkansas.

* None of the five Senators who earned A+ scores by doing the most to bridge the U.S. economic divide are from the South. Of those 14 representatives who earned an A+, only three are from the South: Steve Cohen of Tennessee, Eddie Bernice Johnson of Texas, and Hank Johnson of Georgia.

"The point of this report card is not just to name and shame," writes report co-author Sarah Anderson at Huffington Post. "We also aim to draw attention to the many creative proposals for restoring fairness that deserve more support."

Two of the pending bills on the IPS list would raise revenue for human needs by taxing Wall Street transactions, while the Congressional Progressive Caucus budget would protect social programs by reducing military spending and raising taxes on speculative investments.

"These innovative ideas challenge the oft-asserted notion that austerity is our only viable option," Anderson observes.

For a copy of the report, and an interactive version of the inequality report card map above, click here.

* AL, AR, FL, GA, KY, LA, MS, NC, SC, TN, TX, VA, WV