Polls are open across Boston this morning— and until 8 p.m. tonight— for the presidential primary.

According to Boston election officials, more than 13,000 voters took advantage of "early voting" at City Hall and select neighborhood sites last week. There are 413,710 registered voters in Boston— and just how many of them turn out today is an open question.

City officials reminded voters in Dorchester's ward 17, precincts 1 and 3 that there has been a change in polling location for this primary election. Instead of Codman Square Tech Center on Washington Street, voters in those two precincts should go to the Lucy Stone campus of Roxbury Prep, located age 22 Regina Rd., Dorchester.

Secretary of State William Galvin estimated Monday that 1.5 million Democrats and 350,000 Republicans will cast ballots in today's primaries, a total on the Democratic side that would eclipse the Democratic turnout in the 2016 primary between Hillary Clinton and Vermont Sen. Bernie Sanders.

That works out to just over 40 percent of the 4.58 million eligible voters.

He said close to 230,000 people, including 190,000 Democrats, had already voted early last week, the first time the state has offered early voting ahead of a presidential primary contest.

Since the last presidential primary election in 2016, the state's voter rolls have grown by almost 310,000 people or more than 7 percent, though neither major political party has seen a significant change in its enrollment.

Massachusetts has 4,581,319 voters who are registered to vote in Tuesday's presidential primaries, an increase of 309,484 people or 7.25 percent over the total ahead of the 2016 presidential primaries, according to new data obtained from Secretary of State William Galvin's office.

There are 1,491,600 registered Democrats (32.56 percent of all voters), 462,586 registered Republicans (10.1 percent) and another 2,564,076 unenrolled voters (55.97 percent) who can choose which ballot to pull when they show up at their polling place.

State House News Service reports contributed to this article.