Democrats from Washington at the event could not resist smiling. It was a banner day for civil rights. But, more prosaically, the scenes on both sides of the highway sprinkled optimism on their chances of keeping the White House after Obama.
"The Latino vote is going to stay solid Democratic," said Bill Richardson, a former New Mexico Governor and one of the party's leading Latino figures. "I think the party in deep trouble is the Republican Party. They're digging themselves in a very bad hole with Latino voters for 2016."
Dolores Huerta, a veteran and well-known labour activist, agreed. "I think they can win Congress, but not the presidency. There are 50,000 Latino kids that turn 18 every month - not just on the west coast or in the south-west; you're talking about Georgia, North Carolina, Maryland."
Obama's unilateral action, taken without congressional approval, is a political gamble. A Wall Street Journal/NBC News poll found that 48 per cent of Americans disapproved of him going solo, versus 38 per cent who approved. But 57 per cent supported a pathway to citizenship for illegal immigrants. Analysts on both sides say it could pave the way for another Democrat in the White House, especially if Republicans fall into the trap of overreacting.
Obama electrified the Las Vegas audience. "We're not a nation that kicks out strivers and dreamers," he said.
He exuded brio, a contrast to two weeks ago when the GOP swept the midterm elections, seizing control of the Senate and strengthening its grip on the House, a rout which seemed to repudiate an unpopular, apparently lame-duck President. A conservative agenda - picking apart Obamacare, cutting spending - beckoned. Obama's executive order, made in an emotional White House address on Friday and reinforced in Las Vegas on Saturday, wrested back the initiative, forcing his foes to fight on treacherous terrain.
Mitt Romney sabotaged his 2012 campaign when he urged undocumented people to "self-deport". It alienated Latinos, the fastest-growing group of voters. The GOP's official postmortem made a blunt conclusion: "If Hispanics think that we do not want them here, they will close their ears to our policies." Moderate Republicans later backed a bipartisan Senate immigration bill, hoping to detoxify their image, only to see conservative colleagues in the House kill it.
Latinos, however, turned much of their ire on Obama for his refusal to take unilateral action. Worse, deportation levels soared, prompting the nickname "deporter-in-chief". Disenchantment depressed Latino turnout in the mid-terms, costing Democrats several races.
Last week's executive action leaves about six million of the estimated 11 million undocumented Latinos vulnerable to deportation, and grants only three-year protection to beneficiaries. The most far-reaching aspect is the creation of a "deferred action" programme that will benefit the estimated 3.7 million undocumented immigrants who are parents of US citizens or permanent legal residents. Activists call it a first step to comprehensive reform. Politically, however, it is a leap which has restored Latino faith in Obama and the Democrats.
Latinos lag whites and blacks in election turnout, but their demographic clout - 14 per cent of the electorate - weighs more at every election. Delia Lago, 53, a Vegas hotel worker, had a chilling message for Republicans. She hopes to become a citizen - a voting citizen - next year and has 14 US-born grandchildren, all citizens. Would they ever vote Republican? Her nose wrinkled: "They don't make us feel welcome."
Winners
Reyna Garcia, 32, almost qualified for Obama's 2012 reprieve that allowed hundreds of thousands who came to the US as children to remain. Her mistake was going to work for a cleaning crew instead of enrolling in high school. The Deferred Action for Childhood Arrivals (DACA) programme requires applicants to be attending high school or have graduated. The Mexican native has lived in Alabama for most of the last 17 years and gave birth to three children in the US. Parents of US citizens or legal residents who have been in the country for more than five years are eligible. Her oldest daughter, Yulexi Plata, 14, says it will be a relief for her parents to live without fear of deportation. But after having missed out once, Garcia worries. "I have this fear that I may be missing something again."
Rosa Robles Loreto's 9- and 11-year-old sons were born in Mexico but have lived in Arizona for years. They didn't qualify for a reprieve under the DACA, but Obama is expanding it to lift age restrictions and make anyone eligible who arrived before January 1, 2010. "It feels good my kids are in. They're the reason I'm here fighting," she said. But she was sad that she will not be able to go home. She faces a deportation order after being stopped for a traffic infraction years ago. She has been living in the US illegally since the early 1990s and returned to Mexico to give birth to her sons because she couldn't afford health care.
Losers
Liana Ghica, 49, was a lawyer in Romania who came to the US in 2001. She has unsteady work cleaning houses and managing bookkeeping in the Los Angeles area. Ghica's son studies at the University of California, Los Angeles and is allowed to stay under the DACA programme. However, his mother is ineligible under Obama's plans.
Eduardo Vidal, 36, was deported to Mexico less than three weeks before Obama's announcement, separated from his Salvadoran wife and five US-born children after police in Los Angeles stopped him for a broken tail light and discovered he had three driving under the influence convictions. Vidal spent much of his 22 years in the US cleaning offices. "I don't know my way around. I have no money," Vidal said as he waited with hundreds of others for a free meal at Tijuana's Padre Chava breakfast hall.
Latino power
11 million undocumented Hispanics vulnerable to deportation.
5 million people are expected to qualify under the new measures.
6 million who are in the US illegally will be left out.
14 per cent of the US electorate is Hispanic.
- Observer, AP