The congresssional map proposed by the Governor’s Redistricting Advisory Commission, shown here, uses minority voters in central Maryland to water down the strength of Republican areas. Shaded: The “bizarrely drawn” District 3.

A number of African American leaders in Maryland are justifiably concerned about the congressional map proposed by the Governor’s Redistricting Advisory Commission. As drawn, Maryland would continue to have only two majority-minority districts — the 4th and 7th — and each of those is likely to include fewer minorities than they do now.

Maryland’s minority voters are being used like pawns in a game of electoral chess. Though African Americans account for 30 percent of the state’s population, they are heavily concentrated in the city and county of Baltimore, Montgomery County and Prince George’s County, which creates a redistricting challenge for Democrats. African Americans are the most reliably Democratic voting bloc, but their concentration in the central part of the state makes it hard to offset the more conservative voters in Western, Southern and Northern Maryland and on the Eastern Shore. The party deals with this by dividing up African American communities and joining them to sometimes far-flung regions. In the redistricting commission’s proposal, this has been done in all but the 1st Congressional District on the Eastern Shore.

A single, compact and cohesive majority-minority district could be created by joining all of Baltimore City with its southwest suburbs in Baltimore County — home to much of the county’s black population. But returns from the 2010 gubernatorial election show why this wasn’t acceptable to Democrats. Martin O’Malley and Robert Ehrlich split the Baltimore County vote, while Ehrlich won 54 percent to 43 percent in Anne Arundel County and 65 percent to 34 percent in Harford County. O’Malley , meanwhile, won Baltimore City 82 percent to 16 percent. So the city’s 620,000 residents have been parceled out to three congressional districts. Baltimore residents form the core of the majority-minority 7th District, and “surplus” voters are used to dilute more conservative areas.

Prince George’s County — which O’Malley carried 88 percent to 11 percent — is treated the same way. The saddle-shaped 4th would remain a majority-minority district, but now it takes in much of Anne Arundel (which has been divided among four districts to neutralize Republican strength there). Prince George’s is also used to make sure Democrats dominate the 5th District, which includes Democratic Charles County as well as Republican Calvert and St. Mary’s. Anne Arundel, Calvert and St. Mary’s could form a single cohesive congressional district on the western shore of the Chesapeake Bay — but it would be a Republican district.

Montgomery County voted 68 percent to 31 percent for O’Malley, so it has been divided across three districts (a move the Montgomery County Council opposes). The 6th District, in Maryland’s northwest, voted 62 percent to 33 percent for Ehrlich, but the new map removes most of Frederick County, plus all of Carroll and sections of Baltimore and Harford counties, from that district. To turn the 6th into a marginally Democratic district, those areas have been replaced with a chunk of Montgomery. Much of the rest of Montgomery is in turn used to offset the addition of Frederick and Carroll to the 8th District, with a smidge of the county going to the bizarrely drawn 3rd as well.

The net effect of all of this is a map likely to elect seven Democrats and one Republican. This is no small accomplishment in a state where Republicans routinely receive about 40 percent of the vote. Minority voters, however, are also paying the price. If the lines were drawn more rationally, Maryland’s congressional delegation would include three, and quite possibly four, minorities — a reasonable number, given that the state’s population is more than 40 percent minority. Of course, such a delegation would also probably include three Republicans.

It must be noted that Democrats are not alone in exploiting minorities during redistricting. If Democrats use minority voters to bolster party strength throughout a state, Republicans often pack them into as few districts as possible in states they control. The result is the same: fewer minority members of Congress.

The Voting Rights Act of 1965 prevents states from drawing districts that deny minorities, whether intentionally or unintentionally, a chance to elect a candidate of their choice. There can be little doubt that the proposed map in Maryland is ripe for legal challenge.

The writer is an assistant professor of political science at St. Mary’s College of Maryland. He is the creator of the FreeStater Blog, which is a participant in The Post’s Local Blog Network.

Creative lines

The congressional map proposed by the Governor’s Redistricting Advisory Commission, shown here, uses minority voters in central Maryland to water down the strength of Republican areas. Shaded: The far from “compact and cohesive” District 3.