Clinton has 58 percent support in Miami-Dade County to Trump's 28 percent, according to the WLRN-Univision 23 survey released Wednesday.
Clinton's edge outpaces President Obama's performance in the county in 2012. Obama won Miami-Dade by 24 points en route to taking the key state of Florida by less than one percentage point.
“[Clinton’s lead] is the most that any Democrat has ever gotten, dating back to the 2000 election,” said Fernand Amandi, the Democratic pollster whose Bendixen & Amandi International conducted the poll.
The poll found that the county harshly disapproves of Trump, the GOP presidential nominee.
Seventy-one percent view Trump unfavorably, including 64 percent who say “very” unfavorably. Twenty-seven percent view him favorably.
In contrast, 62 percent see Clinton favorably to 38 percent unfavorable.
“We’ve never seen numbers like these before,” Amandi said. "Ever, ever, ever, ever.”
WLRN-Univision 23 conducted its poll of 600 likely voters via interviews in English and Spanish from Oct. 15-17. It has a 4 percent margin of error.
Clinton leads Trump by about four points in Florida, according to a RealClearPolitics average of polls.