Census officials, including former Gov. Gary Locke, the commerce secretary, announced today that Washington state’s population has grown rapidly enough in the past decade to warrant a new 10th congressional seat.

The state population grew by 14.1 percent since the 2000 census, to 6,724,540 million people. The population growth in the West also was very strong, up 13.8 percent. The U.S. average was 9.7 percent, to 308.7 million people.

As had been projected from preliminary estimates, Washington will gain a 10th district, most likely to be added in the rapidly growth greater Puget Sound region. All of the current districts will be changed significantly, particularly in Western Washington.

Election officials at the state Capitol watched the Census news conference and erupted in cheers as the map flashed on the screen showing that Washington is one of a handful of states to pick up one or more seats. Several states also lost one or more seats.

Secretary of State Sam Reed said he was delighted with the news of a new seat.

“We couldn’t be happier,” he said. “This is a great day for the people of Washington. We gain in clout, with another strong voice in Congress to be added in 2012. We gain an Electoral College vote and our population gain means we get a little larger slice of the pie as federal grants are apportioned out based on population,”

The actual work of divvying up the state in equal-sized congressional districts and legislative districts will be the task of a bipartisan citizen commission. Four voting members – two Republicans and two Democrats – will be appointed by the legislative caucus leaders, and the four will choose a fifth, nonvoting, person to be chairman. The panel will have all of 2011 to develop and finalize the maps, and three of the four voting members must vote for the final product. The Legislature has virtually no role and the governor cannot sign or veto the maps.