Editor’s note: This is the first installment in a two-part series about the 2010 census in South Texas.

A group of long-standing community groups and local officials are ramping up their charge of a massive undercount of South Texas colonias, the low-income communities along the Texas-Mexico border. The move comes after the U.S. Census Bureau released preliminary figures Thursday of the 2010 census, including county breakdowns in Texas.

The Rio Grande Valley, the state’s southernmost region, includes four counties and is home to more than 1 million Texans. In Hidalgo County, the Valley’s most populous, the estimated population in 2000 stood at 569,463, according to census data. Preliminary 2010 census data places the number at 774,769.

Texas boasts more colonias than any other state and the largest colonia population in the nation. More than half of the 400,000 Texans that live in these communities are located in the Valley, according to the Texas Secretary of State’s website.

A network of 11 community groups called Equal Voice Network have worked in the communities for decades and volunteered their help as the bureau began to count the colonias. The groups include some of the most notable of the Mexican-American civil rights era, including La Unión del Pueblo Entero, which César Chávez founded, and ARISE, an empowerment group for colonia women.

“We know these places,” said Mike Seifert, the network’s spokesman. “We know what we’re doing here, and it’s that truth the Census Bureau should remember whenever they’re dealing with us.”

Colonias started gaining popularity in the 1950s, when property developers bought cheap, low-lying land not viable for agricultural production — usually in rural and unincorporated areas — to build houses that often lacked proper infrastructure. The 2,294 colonias in Texas remain an affordable housing option for the state’s low-income families, most notably Hispanic migrant workers and illegal immigrants.

Colonia communities continue to face issues with access to basic amenities, including potable water, electricity and indoor plumbing. Heavy rainfall, for example, will leave some areas flooded for months because of the lack of basic irrigation and drainage systems.

Still, in the past 30 years, colonia residents have organized to get some basic necessities, including their mail, which was key when the 2010 census was set to begin.

The bureau prepared for a large-scale public relations campaign in South Texas, including the colonias. Valley lawmakers and community groups said the Census Bureau told them in January 2010 that colonia residents would receive their forms in their mailboxes.

The media campaign, particularly in Hidalgo County colonias, focused on how easy it was to complete and return the form. The community groups also emphasized that the forms were confidential (no U.S. citizenship questions) and important to return (the census count would determine the allocation of federal funds).

U.S. Rep. Ruben Hinojosa, D-McAllen, distributed 100,000 bilingual fliers about the mail-in form to colonia residents in his district. Seifert credited the community outreach effort — most of it done four months before Census Day — with educating colonia residents about the importance of returning the form. He said the bureau provided adequate resources to help the groups, including census literature and trained personnel.

“The initial response we got from residents was, ‘We wanted to be counted,’” he said. “The census did a great job of having people on the ground.”

However, about a week before Census Day, April 1, colonias contacted some community groups because they did not receive any forms. Some reported unannounced visits from census workers.

“It was on April 1. We thought that was kind of ironic — looking back on it — that it was April Fool’s Day because we didn’t think it was really funny that we got contacted that they were not mailing them out to the colonias, that they were going to walk the colonias,” said Ann Cass, executive director of Proyecto Azeteca, another community group in the network.

Gabriel Sanchez, the Census regional director in Dallas, said the bureau has used door-to-door updates for the South Texas colonias since the 1970s.

“We’ve always done it like that down there because it is so difficult to count,” he said. “

Sanchez said the bureau finalized the door-to-door count, officially called Update/Enumerate, in February 2009.

As the groups scrambled to change their message, Census Bureau Director Robert Groves arrived in the Valley, facing a tough crowd.

This series is made possible by the Helen M. Powell Traveling Fellowship.