The state's third congressional district is squeezed to the width of a single block inside of Baltimore. Traversing the serpentine path of the district of Rep. John Sarbanes', D-Md., would require swimming through Baltimore Harbor.
The most famous recent example of politically minded district-drawing came last decade in Texas. The Lone Star State had already created new House districts after the 2000 Census, and 17 of the state's 32 House members were Democrats.
But when Republicans took control of the state house, then-House Majority Leader Tom DeLay saw an opportunity. Republicans rammed through a new redistricting plan, blowing up the old map to instead favor Republicans, even as Democratic lawmakers literally fled the state in protest.
"You can't get much more extreme than that to take one existing district and chop it into five pieces," said former Rep. Martin Frost, D-Texas, who was one of five Texas Democrats to lose their seats -- and their jobs -- under DeLay's plan. "It is crass political motivation."
Texas stands to add perhaps four House seats after this year's census, according to a recent report from Election Data Services. That's galvanized Democratic interest in the governor's race -- where Democrats think they have a chance to defeat Republican Gov. Rick Perry -- plus state House races, with Democrats within striking distance of taking back the majority.
Florida stands to gain two House seats, while Ohio appears likely to lose two. That means the party in power in the state legislature and the governor's office will have big opportunities to favor their party over the next decade.
"We understand the stakes, and it definitely affects the way resources are allocated," said Carolyn Fiddler, communications director for the Democratic Legislative Campaign Committee.
One offshoot of gerrymandering: partisan polarization. Members of Congress are less likely to compromise with the other party when they know their constituents are politically homogeneous, Frost said.
"It polarizes the two parties the more safe districts you have," he said. "And the more competitive districts you have, probably the more chance there is for some bipartisanship in Congress."
Seven states take redistricting out of the hands of state lawmakers, with independent commissions charged with spreading voters into districts equitably. And two of the nation's largest states could dramatically change the way they re-draw districts after this year's elections, with potentially long-lasting implications.
In Florida, a pair of state constitutional amendments would require the legislature to redraw district boundaries with "fairness," in a manner such that they "may not be drawn to favor or disfavor an incumbent or political party."
The measure is being backed by good-government groups and powerful Democratic-aligned interests. But critics contend that the vague language is a recipe for perpetual gridlock and legal challenges that could leave voting districts carved up by the Justice Department and the courts.