Nate Cohn, New York Times, September 19, 2016

Donald J. Trump has almost no plausible path to the White House unless he wins Florida, a rapidly changing state where Hispanic voters could deal a decisive blow to his chances.

But a new poll, by The New York Times Upshot/Siena College, suggests that Mr. Trump is keeping his hopes alive in Florida, the largest and most diverse of the crucial battleground states. The reason: White voters favor him by a large margin.

Mrs. Clinton leads by a single point, 41 to 40 percent, among likely voters in a four-way race that includes Gary Johnson and Jill Stein. The race is tied in the head-to-head race, 43-43.

The poll, the first of its kind by The Upshot, was based on voter records that allow unusually detailed analysis of the electorate.

It indicates that Mr. Trump leads Mrs. Clinton by 51 percent to 30 percent among white voters–and that includes all white voters, not just those without a college education who have been so vital to his campaign. She’s winning white voters registered as Democrats by only 63 percent to 17 percent.

As has been expected, Mrs. Clinton appears on track for a record-setting state performance among Florida’s Hispanic voters. She leads Mr. Trump by a 40-point margin, 61 percent to 21 percent, more than doubling the 18-point margin President Obama recorded four years ago, according to Upshot estimates. The result is a stronger one for Mrs. Clinton than those of some recent surveys.

She is also doing very well among black voters, though not quite matching the huge margin or the enthusiasm that Mr. Obama enjoyed in 2012, at least not yet.

It’s a story that’s playing out across the country. National polls suggest that the bottom has fallen out for Mrs. Clinton among white voters without a degree, causing her substantial lead in national surveys to all but evaporate.

White working-class voters have given Mr. Trump a lead of three to eight points in recent surveys of Ohio and Iowa–two states with a lot of white working-class voters that Mr. Obama won fairly comfortably four years ago.

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The model suggests that the race has the potential to reshape the familiar political geography of Florida. Miami-Dade County, once fairly competitive, could be on the cusp of becoming a Democratic bastion. Over all, the model indicates that Mrs. Clinton could approach 70 percent of the vote in Miami-Dade–where Al Gore received only 53 percent in 2000–depending on the number of third-party votes.

Heavily Cuban enclaves in west Miami and Hialeah are divided, according to the model, even though they voted heavily for Mitt Romney in 2012. The survey did not sample a large number of Cuban voters, so the findings should be interpreted with caution, but Mrs. Clinton held a tentative lead of 43 to 32 among Cuban voters. Mr. Trump holds only a 60 percent to 25 percent lead among Hispanics registered as Republicans.

The I-4 corridor looks more like a patchwork of racially polarized Democratic and Republican enclaves than a swath of purple neighborhoods. Many areas where Democrats used to be competitive with white voters–north of Tampa or around Daytona Beach, for example–appear to lean to Mr. Trump. It’s gains like these that have helped Mr. Trump stay in the race, despite his loss of ground in South Florida.

There are growing Puerto Rican enclaves south of Orlando poised to vote overwhelmingly for Democrats.

And there are overlooked, rapidly growing and mostly white communities poised to vote overwhelmingly for Mr. Trump. The Villages, a retirement community in central Florida with a population now over 150,000, was the fastest-growing city in the United States in 2013 and 2014, according to the census. It’s expected to break heavily for Mr. Trump.

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