By Hani Shawwa
BBC News, New York
Nube Guaman was 27 when she decided to undertake the arduous crossing from Mexico into the US.
A long crawl through drainage piping - dodging border patrol guards - took her across the border. Once on American soil, "coyotes" - human traffickers - smuggled her further by hiding her under a seat in a van.
In a mixture of Spanish and English, shifting nervously in her seat, she puts the price tag for her journey to Arizona at $6,000.
But en route she was caught at an airport by immigration authorities, and taken to a jail in Los Angeles, California.
"I was there for a week and bail was set at $14,000," she says. "But my family in the US paid it and suddenly I was free."
Unlike many others in her situation she was able to avoid deportation.
Instead, she headed to Brooklyn in New York, to work in a factory.
"It was not easy to get a job because I could not speak English," she says. "I sewed zippers on to shirts and I also worked as a cleaner." That is, when she was well.
If she was ill enough to miss work, she would not get paid.
But however tough the journey, and the work at the end of it, the motives of people like Nube are often entirely straightforward.
Minutemen Civil Defence Corps
According to the World Bank, average income in the US is $43,740. In Ecuador, Nube's home country, it is $2,630 - almost twenty times less.
For her, the lure of better wages and a higher quality of life than at home was irresistible.
And more and more people are following suit.
According to some figures, the number of undocumented immigrants in America is set to increase by half a million people every year, having tripled since 1990.
More than half the US's undocumented workers come from Mexico, directly to the south. People from the rest of Central and South America make up the second largest group, followed by smaller numbers from Asia, Europe and the rest of the world.
Illegal migration has always been a hot political topic in a country known as a melting pot of cultures and races, but in recent weeks the temperature has gone up sharply.
President George W Bush recently completed a tour of Latin America, with a promise to work to reform the way his country deals with the issue of undocumented workers.
An attempt to reform the current system foundered last year, as conservatives from his own Republican party - then the majority in both houses of Congress - shot down his legislation amid concerns about security and enforcement along the country's border with Mexico.
The new Congress, now dominated by the opposition Democrats, has yet to demonstrate whether the White House's rough ride on immigration will continue.
For Democrats, economics rather than security could be the deciding factor in the immigration debate.
The Washington DC-based Pew Hispanic Center estimates that illegal aliens in the US make, on average, about 60% of what legal immigrants or American citizens earn.
That is music to the ears of some US businesses. Although overall illegal immigrants account for 4.9% of the civilian labour force, in agriculture the proportion of illegals rises to nearly a quarter, by some estimates.
Similarly the figure for cleaning is 17%, for construction 14% and for food preparation 12%.
Watching the border
For some, the economic question demands direct action.
"We are not against legal immigrants, just illegals," says Carmen Mercer, Vice President of the Minutemen Civil Defense Corps.
The Minutemen have adopted an iconic name in American history - that of a group of elite soldiers who played a critical role in the American Revolution.
Created in 2005, they are a private-sector, volunteer organisation which believes the US government does not do enough to block movement across the border with Mexico, and have decided to take on the job themselves by monitoring the border and reporting violations.
"Illegal immigrants pose a risk to our economy, health and education system," Carmen Mercer says, arguing that illegal immigrants take away low-wage jobs from students and the unemployed, create extra costs for hospitals, and force schools to adopt Spanish into their curriculum.
New York Immigration Coalition
But those who speak for illegal workers counter that many of the jobs illegals perform are those which few native-born American citizens want.
Without them, they maintain, the economy would stall.
Norman Eng from the New York Immigration Coalition says undocumented workers suffer from a range of misunderstandings.
"They are living in fear of deportation," he says, "they can't find legal employment, and the range of work they end up doing is very limited.
"They have no access to social services. They are forced to live in an underground economy."
Moreover, he believes illegal workers are an asset to society and to the economy at large. "They revitalize declining areas," he says. "They bring in investment through customer spending which also generates sales taxes."
His group wants President Bush to make it easier for illegal immigrants to get legal status and to put a halt to deportations, which split families.
For Nube Guaman, there is a happy ending.
She eventually gained legal status by marrying a US citizen who was also from Ecuador.
It took two years for her green card to come through, but now she has three young children and works in a library in the New York borough of Queens.
"As long as outsiders see better opportunities and wages in America," she says, "the country will always draw people to it."