As a young mother in the Philippines, Lulu Thompson faced a difficult decision. The nurse was struggling to support her three small girls on her salary, but in the U.S. a high-paying job beckoned that would enable her to provide far more for her family. But she'd have to leave them behind.

Thousands of miles away in Honduras, Veisy Cruz found herself with the same unbearable choice. She was working at a supermarket making $100 a month, not enough to support her two young sons.

The Million: How immigrants are transforming Houston, in photos, video and interactives

The mothers both left their children with grandparents, coming to Houston to secure better fortunes for them here. But their journeys and outcomes couldn't be more different. Thompson now is an American citizen making more than $100,000 a year, and her girls have joined her, becoming citizens, too.

Cruz, on the other hand, has lived here illegally for a decade, working in the kitchen of an upscale restaurant. Her younger boy, 10, was reunited with her last summer, but was caught by federal agents and now faces deportation.

The two women and their families illustrate the complexity of the nation's most diverse metropolitan region, with Harris County home to about 1.1 million foreign-born immigrants, and the challenges that poses for policy leaders, according to an analysis of U.S. census data released Wednesday by the Migration Policy Institute. Faced with a large population of immigrants here illegally as well as foreigners on work or humanitarian visas, Houston in many ways represents the many facets of immigration.

On the front lines

"Houston is a bellwether," said William Frey, a demographer with the Brookings Institution, a nonprofit public policy organization in Washington, D.C. "Houston is on the front lines of (immigration) in many directions, so it's a role model for other places but also needs the resources and attention."

The report, commissioned by the Houston Immigration Legal Services Collaborative, provides an in-depth look at the 11-county area's 1.4 million foreign-born, which grew almost 60 percent between 2000 and 2013, nearly twice the national rate. The number of immigrants who, like Cruz, are from Honduras or Guatemala, more than doubled over that period, growing by more than 130 percent to about 76,000 today. Filipinos like Thompson were the area's third-fastest growing nationality, expanding by nearly 90 percent to 34,000 in that time.

The phenomenal immigrant growth rate puts Houston "in a class by itself," said Randy Capps, co-author of the report and director of research for U.S. programs at the Policy Institute, based in Washington, D.C. "The biggest immigrant cities, Los Angeles, Chicago and New York, haven't been seeing this same kind of growth."

What draws foreigners here is what also brings Californians and Midwesterners: jobs, many of them, and a low cost of living. Houston's unemployment rate, around 4.1 percent, remains about a full percentage point below the national average.

Of the more than 245,000 residents Harris County gained in the past three years, a quarter were foreign migrants and 16 percent were Americans from other regions, said Steve Murdock, a former state demographer who heads the Hobby Center for the Study of Texas at Rice University. The rest, nearly 60 percent, were births.

Specialized work visas

The city's flourishing oil and gas and biomedical sectors hire more immigrants every year than nearly any other in the nation, according to federal data analyzed by Myvisajobs.com. In 2013, employers here requested nearly 13,000 specialized work visas, known as H1-Bs, the greatest amount after New York City. The majority are for Asians, especially from the Philippines, India, Pakistan and China. That's how Thompson came here, too, receiving such a visa in the 1980s when the U.S. faced a dire nursing shortage. Only when she landed at the airport did she realize the enormity of her decision.

"It dawned on me then that it was going to take a long time for me to be reunited with my children," said Thompson, who is now 58 and works as a project director for the vice president of medical affairs at M.D. Anderson Cancer Center.

It's, of course, far easier for immigrants like her, who come here legally, to succeed. And most Asian immigrants here do have legal status, whether they are refugees like much of the city's longtime Vietnamese population or are on a work visa. By nearly all the report's benchmarks, Asian immigrants fared the best, with Filipinos leading the pack.

About two-thirds of Houston's Filipinos, many who work in the medical industry, had at least a bachelor's degree, second only to Indians. Filipinos also have the highest median income of all nationalities, about $95,000 annually, compared to $61,000 for U.S.-born workers in Houston.

Though Houston's Asians are growing rapidly, they still represent a small portion of the overall foreign-born population in the area. Mexicans, on the other hand, make up about 45 percent or around 600,000 of the region's immigrants. Nearly half are here illegally. But as Mexico's economy has improved and enforcement at the border has tightened, their growth rate has slowed greatly. The Honduran and Guatemalan population, meanwhile, has skyrocketed.

"They are the more recent groups and tend to be coming in and filling the lower-end jobs beneath the Mexicans, especially in construction and manufacturing," said Capps of the Policy Institute. "Houston's Mexican population is mostly now better established and have had some time to move up, even those without a legal status."

But, as a result, the Central Americans tend to fall on the other end of the success scale. Hondurans, who come from a country where two-thirds live in poverty, have the lowest median income in the region - about $28,000 - with Guatemalans faring only slightly better. They also have the region's lowest levels of education, with 65 percent of Hondurans older than 25 not having completed high school.

"Those are the folks most in the shadows, most at risk, and most in need of services we can offer," said Kate Vickery, project coordinator for the legal collaborative which commissioned the report.

Opportunity for children

Cruz, who came here in 2006 from San Pedro Sula, now makes 16 times as much as she earned back home. She can afford to rent a home on a quiet, shady street in Sharpstown and her two children, Cesar and Angel, are making excellent grades at school.

"I work a lot so they can study and do well," the 30-year-old said. "I hope this country gives them the opportunity to stay."

Thompson, meanwhile, was able to move from her work visa to a green card, then acquired her citizenship, allowing her to bring her children here, too, more than a decade later. "It's been worth it, but only because they could come too," she said.