The new numbers regarding minority votes offer a cautionary note to both Democrats and Republicans.
America's blacks voted at a higher rate than other minority groups in 2012 and by most measures surpassed the white turnout for the first time, reflecting a deeply polarized presidential election in which blacks strongly supported Barack Obama while many whites stayed home.
Had people voted last November at the same rates they did in 2004, when black turnout was below its current historic levels, Republican Mitt Romney would have won narrowly, according to an analysis conducted for The Associated Press.
Census data and exit polling show that whites and blacks will remain the two largest racial groups of eligible voters for the next decade. Last year's heavy black turnout came despite concerns about the effect of new voter-identification laws on minority voting, outweighed by the desire to re-elect the first black president.
And while Latinos are now the biggest driver of U.S. population growth, they still trail whites and blacks in turnout and electoral share, because many of the Hispanics in the country are children or noncitizens.
William H. Frey, a demographer at the Brookings Institution, analyzed the 2012 elections for the AP using census data on eligible voters and turnout, along with November's exit polling. He estimated total votes for Obama and Romney under a scenario where 2012 turnout rates for all racial groups matched those in 2004. Overall, 2012 voter turnout was roughly 58 percent, down from 62 percent in 2008 and 60 percent in 2004.
"The 2008 election was the first year when the minority vote was important to electing a U.S. president. By 2024, their vote will be essential to victory," Frey said. "Democrats will be looking at a landslide going into 2028 if the new Hispanic voters continue to favor Democrats."
In recent weeks, Republican leaders have urged a "year-round effort" to engage black and other minority voters, describing a grim future if their party does not expand its core support beyond white males.
The 2012 data suggest Romney was a particularly weak GOP candidate, unable to motivate white voters let alone attract significant black or Latino support. Obama's personal appeal and the slowly improving economy helped overcome doubts and spur record levels of minority voters in a way that may not be easily replicated for Democrats soon.
Romney would have erased Obama's nearly 5 million-vote victory margin and narrowly won the popular vote if voters had turned out as they did in 2004, according to Frey's analysis. Then, white turnout was slightly higher and black voting lower.
More significantly, the battleground states of Ohio, Pennsylvania, Virginia, Florida and Colorado would have tipped in favor of Romney, handing him the presidency if the outcome of other states remained the same.
"The 2012 turnout is a milestone for blacks and a huge potential turning point," said Andra Gillespie, a political science professor at Emory University who has written extensively on black politicians. "What it suggests is that there is an 'Obama effect' where people were motivated to support Barack Obama. But it also means that black turnout may not always be higher, if future races aren't as salient."
Whit Ayres, a GOP consultant who is advising GOP Sen. Marco Rubio of Florida, a possible 2016 presidential contender, says the last election reaffirmed that the Republican Party needs "a new message, a new messenger and a new tone." Change within the party need not be "lock, stock and barrel," Ayres said, but policy shifts such as GOP support for broad immigration legislation will be important to woo minority voters over the longer term.
"It remains to be seen how successful Democrats are if you don't have Barack Obama at the top of the ticket," he said.
The numbers show how population growth will translate into changes in who votes over the coming decade:
—The gap between non-Hispanic white and non-Hispanic black turnout in 2008 was the smallest on record, with voter turnout at 66.1 percent and 65.2 percent, respectively; turnout for Latinos and non-Hispanic Asians trailed at 50 percent and 47 percent. Rough calculations suggest that in 2012, 2 million to 5 million fewer whites voted compared with 2008, even though the pool of eligible white voters had increased.
—Unlike other minority groups, the rise in voting for the slow-growing black population is due to higher turnout. While blacks make up 12 percent of the share of eligible voters, they represented 13 percent of total 2012 votes cast, according to exit polling. That was a repeat of 2008, when blacks "outperformed" their eligible voter share for the first time on record.
—Latinos now make up 17 percent of the population but 11 percent of eligible voters, due to a younger median age and lower rates of citizenship and voter registration. Because of lower turnout, they represented just 10 percent of total 2012 votes cast. Despite their fast growth, Latinos aren't projected to surpass the share of eligible black voters until 2024, when each group will be roughly 13 percent. By then, 1 in 3 eligible voters will be nonwhite.
—In 2026, the total Latino share of voters could jump to as high as 16 percent, if nearly 11 million immigrants here illegally become eligible for U.S. citizenship. Under a proposed bill in the Senate, those immigrants would have a 13-year path to citizenship. The share of eligible white voters could shrink to less than 64 percent in that scenario. An estimated 80 percent of immigrants here illegally, or 8.8 million, are Latino, although not all will meet the additional requirements to become citizens.
Based on reporting by The Associated Press.