But see Ronald Brownstein, at the Atlantic, "Trump, Clinton, and the Realignment of Battleground States":
CLEVELAND—The tumultuous 2016 presidential race appears poised to realign the states at the tipping point of American politics.
Since Bill Clinton’s first victory in 1992, Democratic presidential candidates have consistently run better in the aging, predominantly white and heavily blue-collar swing states clustered in the Rustbelt than in the younger, more diverse, and increasingly white-collar swing states arrayed across the Sunbelt. That pattern, in fact, has largely shaped presidential races since passage of the Civil Rights Act of 1964 fractured the century-long Democratic control of the “solid South.”
But now public polls and private assessments alike show Donald Trump running more strongly against Hillary Clinton in several of the key Rustbelt battlegrounds than in their Sunbelt counterparts.
With blue-collar whites providing the core of Trump’s support, the Rustbelt has emerged as his most—and perhaps only—plausible path to an Electoral College majority. Simultaneously, Democrats are increasingly viewing Sunbelt states that not long ago were considered safely Republican as the closest thing to a firewall for Clinton, largely because of the resistance to Trump among minorities and white-collar whites. “This shift was probably coming anyway because of the changing demographics of the Sunbelt, but Trump radically accelerates it on both ends,” said long-time Democratic strategist Paul Begala, a senior adviser to the pro-Clinton Priorities USA political action committee.
The trend was underlined last week by the release of a flurry of NBC/Marist College/Wall Street Journal polls that showed Trump even with Clinton in Ohio and just narrowly behind in Iowa, while lagging by virtually identical margins of six to nine percentage points in Virginia, North Carolina, and Florida in the Southeast, and Colorado in the Southwest.
Political strategists in both parties generally rank those four states, plus Nevada, as the five true swing states in the Sunbelt. New Mexico, a sixth Sunbelt state, was competitive during the George W. Bush years, but both sides now place it safely in the Democratic camp. Together, the five most competitive Sunbelt states offer 72 Electoral College votes (led by Florida with 29).
Likewise, strategists identify five Rustbelt states as key battlegrounds: Ohio, Iowa, Wisconsin, Pennsylvania, and Michigan. (The final state that both sides have treated as competitive in recent elections is New Hampshire, which is geographically distant from both clusters, but demographically and economically more closely resembles the battlegrounds in the Rustbelt than the Sunbelt.) The five Rustbelt battlegrounds offer 70 Electoral College votes (led by Pennsylvania with 20).
Just gaining ground in the Rustbelt won’t be enough for Trump if he can’t contain his losses in the Sunbelt. Even if Trump flipped all five of the Rustbelt swing states—each of which backed President Obama over Mitt Romney in 2012—he would still lose the election if he can’t win any of the five Sunbelt swing states, assuming no other states changed hands.
The shifting balance in these two key groups of swing states reflects, above all, the changing demography of each party’s electoral coalition. The working-class white voters underpinning Trump’s support represent a much larger share of the vote across the Rustbelt than the Sunbelt, whether using data from the exit polls or the Census post-election survey (which consistently identifies non-college whites as a large share of the electorate than the exit polls do). The Census results identify non-college whites as at least 54 percent of 2012 voters in all five Rustbelt states—and no more than 44 percent in any of the Sunbelt states. And except for Florida, the Rustbelt states, as a group, are also generally older, at a time when Republicans are dominating among whites older than 45.
Contrasting dynamics are molding the Sunbelt states. Diversity is the most important. The non-partisan States of Change project has projected that from 2008 to 2012 the minority share of eligible voters will rise by more in each of the Sunbelt swing states than in any of the Rustbelt battlegrounds, with the biggest increases registered in Nevada (a stunning 7.3 percentage points), Florida (4.5 points), and Colorado (4.3 points). In each of those states except Colorado, the States of Change model projects that the white share of eligible voters will dip below 70 percent in 2016. By contrast, the model projects that whites will still comprise at least 80 percent of eligible voters this year in all of the Rustbelt swing states except Michigan (where it will dip only to 78 percent).
Democrats have also benefited because college-educated whites, who have been grown warmer toward the party since the 1990s, generally comprise a larger share of the total white vote in the Sunbelt than Rustbelt battlegrounds. While the Census found that whites holding at least a four-year college degree represented only a third or less of all white voters in 2012 in Ohio, Iowa, and Michigan, they comprised at least 45 percent of all whites voting in Virginia and Colorado. (College whites clustered at 36 percent of the total white vote in Pennsylvania, Wisconsin, and Nevada and slightly above that in Florida and North Carolina). This dynamic may prove especially important this year with most national polls showing Clinton even or ahead of Trump among college-educated whites—a group no Democratic presidential nominee has carried in the history of modern polling dating back to 1952.
It’s possible that this evolving geography could tip other states from both buckets into the competitive category. When the Trump campaign recently identified 17 states as 2016 battlegrounds in a private briefing for a group of congressional Republicans first reported by the Wall Street Journal, it included reliably Democratic Minnesota in the Rustbelt as a state it hoped to contest. It also identified Republican-leaning Arizona and Georgia in the Sunbelt as diverse states it would need to defend. (Somewhat incongruously, it also included red-tinted Missouri and Indiana from the Rustbelt as states it thought it might need to protect.) But at this point few Democrats—including inside Clinton’s campaign—say they believe any of those will become truly competitive.
Obama’s two victories signaled growing Democratic strength in the Sunbelt, but despite some early party fears, displayed no erosion in the Rustbelt: Compared to the 1992 to 2004 period, Obama improved on the Democratic performance in both groups of states. This year, though, the polling raises the possibility that Trump could advance in the Rustbelt and retreat in the Sunbelt, leaving Clinton potentially more reliant on the latter than the former. That would mark a major reversal...