Town and city clerks in the Merrimack Valley fear low participation by state residents on the 2010 Census could cost Massachusetts a seat on Capitol Hill.

Along with the 435 seats in the U.S. House of Representatives, federal aid is also divided among the 50 states based on decennial Census population figures.

To do their part and ensure the Bay State keeps its 10 U.S. representatives and maintains its current share of federal money, area clerks say they are planning ahead to help maximize Census participation in their communities.

Census forms will be sent to every household in the United States in March.

"You're competing really with the rest of the country," said North Andover Town Clerk Joyce Bradshaw. "When you're looking for federal dollars and representation, it's critical. This is really a full commitment from all of us that we get every single person counted that should be counted."

In Haverhill and Methuen, city clerks have already met to talk Census strategy with Congresswoman Niki Tsongas, D-Lowell, and Secretary of the Commonwealth William Galvin.

Methuen City Clerk Christine Touma-Conway said her office will form a "Complete Count" committee this summer in conjunction with U.S. Census Bureau.

The city also plans to reach out to church and community leaders to help ensure Methuen's immigrant populations participate in the Census. Touma-Conway said the creation of promotional Census materials in different languages will be considered.

"We'll try to bring in as many people as we can," she said.

Lawrence City Clerk Bill Maloney said his office will reach out to churches, neighborhood associations and other community groups to boost participation.

"It's their reach to the community that is important," said Maloney. "You need to go into it with from an open and positive standpoint to try to obtain as much response as possible."

Haverhill City Clerk Margaret Toomey said her office is still drawing up exactly how the city will promote the Census.

"That's what we're in the process of considering, how best to go about this," said Toomey. "Obviously, there's concern, so I think it's very important that people respond."

The population of Massachusetts in 2000, when the last federal Census was conducted, was 6,349,113, according to the U.S. Census Bureau Web site.

The state has grown 2.3 percent in the eight years since, based on the bureau's 2008 population estimates. The average growth per state for that time in the United States is 8 percent, according to the Web site.

Virginia, which has 11 members of Congress, grew 9.7 percent in that time, and Arizona, which has eight U.S. representatives, grew at a 26.7 percent rate since 2000.

The 2000 Census was also seen as critical for Massachusetts to retain representation in Congress, according to Andover Town Clerk Randy Hanson.

"We were on the brink 10 years ago of not getting the count we needed to retain a House representative," Hanson said. "It's even more crucial this time, because of the changes of population."

Andover and North Andover are both partnering with the League of Women Voters of Andover/North Andover for a promotional Census campaign.

Hanson said together they have created a slogan and logo that will be distributed on letterhead, brochures and on Web sites in the months leading up to the Census.

Census workers across the country are canvassing door to door this summer, identifying the global-positioning coordinates of every housing unit in America.

After the initial Census mailings go out in March, a second Census form will be sent to households that do not respond to the initial questionnaire.

Households that still do not respond will be called or visited by a Census worker.

The Census Bureau must submit state population totals to the president by Dec. 31, 2010.

The Census takes less than 10 minutes to complete, according to the Census Bureau Web site.

"It's a short form, I think 10 questions," said Hanson. "It doesn't take a long time."

"If we under-count, we're going to be in trouble, because other parts of the country are growing so fast," said Hanson.