Speakers at the Republican and Democratic national conventions waxed eloquently and passionately about their families' humble beginnings as immigrants whose hard work delivered the American Dream.

New Jersey Gov. Chris Christie proudly thanked his Irish/Sicilian immigrant parents for laying the foundation for his success.

Potential first lady Ann Romney beamed about her Welsh immigrant family who toiled in the mines before they prospered in the land of opportunity.

Marco Rubio, a Florida senator and prominent Republican convention speaker, poignantly described how he graduated from law school and could stand before the convention podium because his father left Cuba to stand working behind a bar.

At the Democratic convention, keynoter Julian Castro, the cherubic mayor of San Antonio, extolled how his grandmother migrated from Mexico to work as a maid and cook so "instead of a mop, I could hold this microphone." Lumps plugged some throats when he quoted her, "Que Dios te bendiga," a familial phrase in Mexican-American households that had been elevated onto a worldwide stage.

Antonio Villaraigosa, the Los Angeles mayor and the Democratic National Convention chairman, talked about emerging from the tough Boyle Heights area to serve the U.S. city with the second largest Latino population.

The storybook embrace of immigrants was one of the few bipartisan bridges over the chasms of differences between the conventions. Immigrants were heroes. The greeting-card warmth buoyed the audiences with patriotic fervor.

It was no accident. Immigrants and Hispanics were prominent because the Hispanic vote has reached critical mass and will influence swing states including Illinois, Colorado, Florida and Nevada.

Big states such as California and New York are rich in electoral college votes and presumed to go Democratic this fall due in part to the Hispanic vote.

Analyzing the "Hispanic vote" is highly layered and riven by geography, nationality and the degree to which Hispanics have acculturated. Politically, about two-thirds of the Hispanic voting populace leans Democratic, but Republican Latinos have captured Senate and gubernatorial races.

Numbers are revealing, and context is crucial when analyzing regional Hispanic politics.

The Hispanic population grew at four times the national rate in the 2010 U.S. Census. Politics eventually devolves into numbers and demographics, so many politicos took note.

Immigrants from Cuba like Mr. Rubio's family are welcomed and given an immediate path toward legalization because of the U.S. government's anti-Castro position.

Among the 52 million Hispanics in the United States, about 4 percent, or 1.9 million, are Cuban-Americans. Most live in Florida and many vote Republican because of the U.S. stance against Cuba.

For scope, 33 million Hispanics are of Mexican descent, in some cases have U.S. lineages over multiple generations and might precede the U.S.-Mexican War that ended in 1848. The cliche is that the international border passed them, not the other way around.

Also, the annual visa allotment for Mexican emigres is tiny and quickly disappears. They can't get in line for a line already closed.

Overall, Republicans have blocked comprehensive immigration reform, which would include legalizing more immigrants and temporary agricultural workers while also increasing homeland security.

Immigration has been narrowly cast into a brawl about "illegal immigration" and dwells on tougher law enforcement instead of developing a long game in which qualified immigrants would help the U.S. economy rebound.

The cuddly Republican convention tone is belied by phrases like "Take Back Our Country," "self deportation" "border walls" and "militarize the border." Our nation has 40 million people, or 13 percent of its population, who are foreign born, an estimated 12 million who have an illegal immigration status.

Castro and Rubio aren't immigrants. They were born U.S. citizens in immigrant families, a trend today regardless of the parents' legal status.

Both speakers stressed how access to a good education made their successes possible. Immigration is a core issue, but Hispanics rank lowest nationally in educational attainment and among people with health insurance. For immigrants, mastering English is a key that opens doors.

Castro explained how his family story really is ordinary and not so special. He spoke of immigrants working extraordinarily hard to build a life here, which spans many generations and many peoples worldwide.

Immigrants today are as noble and motivated as their forebears. But the political milieu has changed, and the world has become more volatile.

Rose-colored nostalgia feeds the soul. But immigrants want a chance to earn a life here through hard work, like others before them. Public policies should respect their contributions and not discard them as job stealers or cultural corrosives.

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Gilbert Bailon is the editor of the St. Louis Post-Dispatch. Distributed by MCT Information Services