WASHINGTON -- In the waiting room at La Clinica del Pueblo, a community health center in Washington, signs in Spanish encourage patients to "Empower yourself!" and sign up for insurance coverage.

Adults slump in chairs, scribbling on application forms, texting friends, waiting. In a tiny office a few feet away, William Joachin, the center's patient-access manager, confronts the frustrations of trying to navigate the federal health care law for the thousands of immigrants who flood the clinic each year.

A year after open enrollment under the Affordable Care Act began, 1 in 4 Latinos in the United States do not have health insurance, according to new Census Bureau data, more than any other ethnic population. And most states have few backups in place to help those in the coverage gap. Latino immigrants are the hardest-hit: Foreign-born Hispanics are more than twice as likely to be uninsured as are U.S.-born Hispanics, according to census data compiled by the Pew Research Center.

A variety of factors account for this, including a lack of culturally specific outreach programs, language barriers, financial concerns, frustration with the law's complexities and fears that applying could reveal a relative's illegal status.

Illustrating some of these challenges was the woman in Joachin's clinic who grew up in a Honduran refugee camp and couldn't read or write in any language. As a legal resident, she was eligible to purchase health insurance through the exchanges created by the law, Joachin said, but she didn't know how to spell her name. With help, she had applied back in March, but she was still waiting for a reply.

Among the people hard to get covered are immigrants from El Salvador, former activists and some who fought against their government during a civil war that ended in 1992; many are exceedingly wary of any government program, even health insurance.

Then there's the "mixed status" family with the son a citizen, the mother with temporary protected status, the father with a green card, the grandmother with a visa and the uncle seeking asylum.

"That's when it gets complicated," Joachin says.

Fifty-six percent of noncitizen immigrants in the United States are Latino; many of them are in the country illegally and are not eligible to purchase health insurance through the health exchanges, even if they can afford to pay.

Naturalized citizens from Latin America fare better than noncitizens; 21 percent are uninsured, compared with 49 percent of Latin American immigrants who are not citizens. (About 14 percent of all U.S. residents do not have insurance.)

Overall, children are more likely to have health insurance, thanks to a number of safety-net programs, including Medicaid, the joint federal-state health care program for the poor, and the federal Child Health Insurance Program (CHIP). Despite this, Latino children are more than twice as likely as white children to be uninsured, according to the National Council of La Raza (NCLR), a civil rights and advocacy organization for Hispanics that is based in Washington. One in 6 Hispanic children do not have health coverage.

By comparison, 1 in 10 African American children lack health insurance, while 1 in 11 Asian-American children are uninsured.

Making matters worse, health advocates say, is that most states have done little to remedy the problem. Twenty-four states have chosen not to expand Medicaid as permitted by the federal law, including Texas and Florida, which have the second- and third-largest Latino populations in the country.

"Just with (Florida and Texas) alone, as long as they don't pass Medicaid expansion, we're going to be left with millions of Latinos uninsured," said Alejandra Gepp, associate director of the NCLR's Institute for Hispanic Health. "The cost to (states of) having this large segment of uninsured people is huge, because people end up using the emergency room as services."

The number of Latinos with health care coverage has increased 5.3 percent since the federal law took effect, according to the Robert Wood Johnson Foundation. But many remain uninsured.

One reason is that immigrants are more likely to be lower-income and to be working in jobs that don't offer insurance, according to Jennifer Sullivan, director of the Best Practices Institute for Enroll America, a nonprofit created to expand health care coverage.

Even if their jobs do offer health insurance, it's often too expensive, Gepp said.

"Let's say you're making $10 an hour. After taxes, you're left with probably a check of no more than $400 a week at most," Gepp said. "If you have to pay $200 in health insurance each month, many decide not to purchase it."

Language is also a big issue. The Spanish version of the federal health insurance exchange information was poorly translated. In describing monthly premiums, for example, the website used the word "prima" for premium, which also means "female cousin" in Spanish.

States that created their own exchanges often did no better. Oregon used the often awkward Google Translate. California, despite its large Latino population, offers poor translations, according to Lisa Clemans-Cope, a researcher at the Urban Institute's Health Policy Institute.

Trust is also a major factor for families who fear that enrolling could jeopardize their immigration status, despite government reassurances to the contrary, said Sonal Ambegaokar, senior attorney at the nonprofit National Health Law Program. "But if there's an immigration raid in that community, it's not very reassuring."

There are no statewide assistance programs for undocumented immigrants and for legal foreign-born residents who do not yet qualify for aid, according to Gepp. People with permanent-residency status -- - that is, those who have what is often called a green card -- must have been in the country for at least five years to qualify for Medicaid. There is no restriction on getting insurance under the health law as long as applicants are in the country legally and have a Social Security number.

In California, Democratic state Sen. Ricardo Lara this year introduced the Health for All Act, which would expand coverage for all Californians, regardless of immigration status.

The District of Columbia has the Healthcare Alliance, which provides care for low-income people regardless of immigration status. But because the program does not offer mental health and substance abuse treatment, it does not meet minimum standards for health insurance as mandated by the federal law, according to La Clinica's Joachin.

Other states rely on a patchwork system of safety-net providers, including public and not-for-profit hospitals, migrant health centers and community health centers, according to a Hastings Center report.

Illinois, for example, which has the nation's fifth-largest Latino population, provides coverage for all low-income children under 19, even if they are undocumented.

In Virginia, legal immigrants who are pregnant or younger than 19 may qualify for Medicaid or the FAMIS program. Other immigrants may qualify for emergency care, even if they are undocumented.

In Maryland, the quality of care an uninsured immigrant can receive will vary greatly across counties, said Del. Ana Sol Gutierrez, D-Montgomery.

"It's hard for me to understand why we prohibit people from buying health insurance," Gutierrez said. "That's kind of crazy. I'm not saying (undocumented people) should have the free coverage. I'm sure many of them would be able to pay."