WASHINGTON - The U.S. Supreme Court on Tuesday upheld West Virginia's congressional redistricting plan against a challenge that small population variations among its three congressional districts violate the Constitution.The justices, in an unsigned opinion, reversed a lower federal court ruling that struck down the plan because of the population differences.The high court said the West Virginia plan easily passes muster and said the population variations are too small to trigger constitutional concerns about the principle of one person, one vote. In addition, the court said the plan adopted by the West Virginia legislature served other legitimate goals, including keeping counties intact and not pitting incumbents against each other."It is clear that West Virginia has carried its burden," the high court said.The justices had previously blocked the ruling to allow the state to conduct elections under the map approved by state lawmakers.The lower court still can consider challenges to the plan under the state Constitution.Both the state House of Delegates and Senate passed the map with bipartisan and nearly unanimous margins. The difference between the smallest and largest districts was about 4,900 people.The Jefferson County Commission challenged the redrawing, which moved one county from one congressional district to another.A panel of three federal judges voted 2-1 in concluding that state officials failed to justify why one district contained several thousand more people than the other two, especially when other proposals contained smaller differences in population.The judges said that improved technology that allows precise line-drawing also had made what would have been a minor variation in an earlier era into a major issue today.But the Supreme Court said the judges' reasoning was faulty. "Nothing about technological advances in redistricting and mapping software has, for example, decreased population variations between a state's counties," the justices said.The case is Tennant v. Jefferson County Commission, 11-1184.