This is a horribly misleading headline from Fox News, which is all too typical of their bias. If you actually bother to read the article, you will see the following two passages right next to each other:
"In Miami-Dade, 152,964 registered Republicans cast early ballots, leading Democratic voters, 146,371 of whom turned out early to the polls, according to state data on Friday."
However, the passage right below that reads:
"Meanwhile, Democrats who mailed in their ballots in the county nearly doubled that of Republicans, 208,803 to 116,040."
If you add up the registered Republicans who cast early ballots in-person (152,964) along with those registered Republicans who mailed in their ballots (116,040), that gives you a total of (152,964 + 116,040 = 269,004). That means that 269,004 Registered Republicans have already voted.
If you add up the registered Democrats who cast early ballots in-person (146,371) along with those registered Democrats who mailed in their ballots (208,803), that gives you a total of (146,371 + 208,803 = 355,174). That means that 355,174 Registered Democrats have already voted.
Finally, that means that (355,174 - 269,004 = 86,170) 86,170 more Registered Democrats have already voted, than Registered Republicans in Miami-Dade County.
Fox News is trying to make it appear as though the early voting favors Trump in Miami-Dade County, but that isn't the case. More registered Republicans are voting in person in Miami-Dade but that isn't a surprise. In fact, it's typical of what we are seeing across the country. Democrats are trusting the mail, because their party nominee hasn't spent the last four months casting doubt on the legitimacy of mail-in voting.