About 1.5 million minority residents in the U.S. were not counted in the 2010 census, the government announced March 22, prompting concern from civil rights groups.

In the lead-up to the 10-year survey, the government launched an extensive outreach campaign aimed at historically hard-to-count Black and Hispanic communities, pushing census costs to an unprecedented $15 billion.

Still, officials missed about 2.1 percent of Black Americans and 1.5 percent of Hispanics and also missed the mark with renters and young men, according to a post-enumeration survey, which assesses the accuracy of the census. Those rates of the uncounted are comparable to the outcome in the 2000 population count.

“While the overall coverage of the census was exemplary, the traditional hard-to-count groups, like renters, were counted less well,” said Census Bureau Director Robert Groves in a recorded press conference. “Because ethnic and racial minorities disproportionately live in hard-to-count circumstances, they too were undercounted relative to the majority population.

“Our belief is that without our outreach, our numbers would have been much, much worse,” he added.

Also undercounted were American Indians and Alaskans on reservations to the tune of almost 5 percent.

Those numbers are troubling to many within the civil rights community.

“The U.S. Census Bureau is to be commended for its unprecedented efforts to reach all Americans to participate in the 2010 Census,” said Marc Morial, president of the National Urban League (NUL), in a statement. “While the overall coverage of the Census has improved over the last decade, we are deeply troubled by the persistent and disproportionate undercount of our most vulnerable citizens—people of color, very young children and low-income Americans.”

This post-census assessment has often been a source of controversy, given the political, economic and social outcomes at stake. Some, like the NUL, have argued that undercounts put minorities at a disadvantage and the government should adjust the official numbers to reflect the unaccounted for persons.

“As the composition of America changes, this differential undercount will continue to harm these individuals by presenting an incomplete picture of who they are ….,” Morial said. “At a minimum, the Census should have the ability to make an adjustment in the official count to ensure that these individuals enjoy the political representation and fiscal resources to which they are entitled.”

Census officials acknowledged their failing with regard to minorities, renters and younger people. However, they said they are satisfied with their general performance.

Overall, the survey found that the 2010 Census had a net overcount of 0.01 percent, or about 36,000 people, which was mostly attributable to duplicate counts of affluent whites owning multiple homes, an AP article said.

That’s compared to an estimated net overcount of 0.49 percent in the 2000 census and a net undercount of 1.61 percent in 1990.

“On this one evaluation — the net undercount of the total population — this was an outstanding census,” Groves said. “When this fact is added to prior positive evaluations, the American public can be proud of the 2010 Census their participation made possible.”