Dalila Ruiz walked into the county fairgrounds building in Jordan with her two children, her niece and her mother, Dominga. They had driven from Savage, about 20 miles away, in a borrowed car to make it to the free clinic.

Her 70-year-old mother, who was visiting from El Salvador, had been complaining of prickly pain in her eyes, headaches, congestion, teary eyes, stomach pain and fevers. "She doesn't have health insurance, and we can't afford to go to the doctor," Ruiz said.

Nurse Jennifer Doble took Dominga's medical history, then escorted the family to the clinic: a 31-ton truck parked outside.

The trailer, equipped with a defibrillator, a crash cart, blood pressure monitors, wheelchair lift, chest X-ray suite and an electrocardiogram, is one of a handful of mobile health clinics in Minnesota that are part of a strategy to bring medical care to the state's under- and uninsured.

The behemoth clinic visits one of three locations in Scott County about every two weeks. Its owner, the Shakopee Mdewakanton Sioux Community, lends it to the county as part of a partnership to increase access to care in Scott County, one of 169 areas in Minnesota federally designated as having a shortage of primary care professionals.

The truck is meant to be a gateway "for patients who have no way into the health care system," said its staff physician, Dr. Mike Wilcox.

Mobile clinics date back to 1935, when members of the Alpha Kappa Alpha sorority started the Mississippi Health Project to bring medical care and education to residents who lacked doctors.

A growing emphasis on preventive care has inspired hospitals, community clinics and public health departments to use mobile units to serve people with limited access to health care.

But mobile clinics can also help control health care costs by giving patients an alternative to costly emergency room visits, said Dairen DeLorenzo, executive director of the Mobile Health Clinics Association, which represents about 300 organizations that operate mobile clinics nationwide.

About 2,000 mobile units across the country offer primary and preventive care, dental care, mammography screenings and mental health services to about 7 million people a year, according to an estimate by www.MobileHealthMap.org.

In Minnesota, where an estimated 9 percent of the population lacks health insurance, seven mobile clinics are registered with the site. Also, Open Door Health Center in Mankato began mobile health and dental clinics this year.

Many of the clinics do not travel to remote parts of the state, but almost all serve a large share of patients who lack insurance or transportation.

"Our goal was to park in places that were centrally located," said Jennifer Theneman, Open Door's director of Mobile Health Services.

Working in a mobile clinic presents challenges not seen in a traditional setting. Patients and providers are often in closer quarters. Clinics may also lack the equipment of brick-and-mortar clinics, which means the staff needs to be creative, experts say. But "the care is the same quality," said Clarence Jones, outreach director at Southside Community Health Services.

Generally, mobile clinics aim to introduce patients to nearby doctors who can become their permanent providers.

But that model doesn't always pan out. Some patients, like Meri Gorenca, 63, and her husband, Sinan, 72, of Savage, make mobile clinics their preferred provider. The Gorencas, who immigrated from Albania three years ago and don't have health insurance yet, have been going to the Scott County clinic for about a year.

Their pre-existing conditions -- high blood pressure, high cholesterol and heart problems -- make it difficult for them to purchase private health insurance. And because the staff is professional, thorough and welcoming, they keep coming back, they say.

So far, repeat visitors have not been a problem, said Merrilee Brown, Scott County's public health nursing director. And staff follow-ups with patients are meant to ensure they have found, or are on their way to finding, a stable medical home.

How many mobile clinic patients actually enter the traditional health care system, however, is unknown, making it hard to assess how effective clinics are at linking patients to health care providers.

However, individual patients seem to be benefiting.

In the clinic, Wilcox can perform checkups, cholesterol and pregnancy exams, tests for sexually transmitted diseases and cultures for strep throat. He and community paramedic Kai Hjermstad can treat patients for routine maladies like allergies and acne or more serious conditions like joint pain and diabetes.

Inside the truck, Dominga Ruiz joked with Wilcox and Hjermstad, who mostly communicated through Dalila. But when Hjermstad asked her to stick out her tongue so he could examine her throat, he stuck out his own to illustrate.

Wilcox diagnosed high blood pressure in his new patient, prescribed new medication and called in the prescription to a pharmacy near the family's home. He then asked Dalila to bring her mother back to the Savage clinic in two weeks for another checkup.

Dominga looked to her daughter for a translation, then smiled.

"Esta bien," she said. "Que bueno!"