The 5 Largest Half Marathons in the United States

A handful of half marathons in the United States have grown large enough to require serious logistics — corral waves, staggered starts, citywide road closures. This list covers the races that have earned that scale through decades of history, strong entry demand, or a built-in draw like a theme park or a music festival woven into the course. Field-size rankings shift from year to year, so the focus here is on what makes each race durably massive rather than a specific year's finisher count.

For half marathons built for scale outside the US, see the 5 largest half marathons in the world. If you're still deciding what you actually want out of race day, how to find a half marathon walks through choosing by season, course profile, and field size.

1. OneAmerica 500 Festival Mini-Marathon — Indianapolis, Indiana

Dating back to 1977, the 500 Festival Mini-Marathon is one of the longest-running and largest half marathons in the country, tied to the month-long celebration around the Indianapolis 500. Its signature feature is the finish: the course routes runners onto the Indianapolis Motor Speedway for a lap of the famous track before the finish line. Typically held in early May, it draws a huge regional field along with runners traveling specifically for the Speedway finish.

2. United Airlines NYC Half — New York City

Organized by New York Road Runners, the NYC Half is a point-to-point course through Manhattan that has become one of the most competitive-entry half marathons in the country. Entry runs through a lottery, a time qualifier, or NYRR's guaranteed-entry programs for members who race and volunteer at NYRR events (program rules change from year to year, so check NYRR's current entry requirements). That competitive entry process, combined with the scale of running through Manhattan on closed roads, makes it one of the largest and most sought-after half marathons in the US.

3. Rock 'n' Roll Nashville (Country Music Half Marathon) — Nashville, Tennessee

Part of the Rock 'n' Roll Running Series, this race routes through Nashville's music-venue-dense downtown with live bands stationed along the course — a format the Rock 'n' Roll series pioneered and that Nashville, as the birthplace of country music, delivers especially well. It's consistently one of the largest events in the entire Rock 'n' Roll series and a fixture on the national half marathon travel circuit.

4. Walt Disney World Half Marathon — Lake Buena Vista, Florida

Part of runDisney's Walt Disney World Marathon Weekend, this race starts before dawn and routes through multiple Disney theme parks, drawing a national field of runners willing to travel specifically for the Disney experience. It's also part of larger multi-race weekends like the Goofy's Race and a Half Challenge and the Dopey Challenge, which stack additional race distances on top of the half and pull in runners chasing those medals as much as the half marathon itself. Registration for Marathon Weekend opens far in advance and regularly sells out.

5. Brooklyn Half — Brooklyn, New York

Also organized by New York Road Runners, the Brooklyn Half has historically been one of the largest half marathons in the country by finisher count. The course runs from Prospect Park out to a finish on the Coney Island boardwalk, and entry works the same way as the NYC Half — lottery, time qualifier, or NYRR's guaranteed-entry programs.

Other Large US Half Marathons Worth Knowing

How to Read Field-Size Rankings

Treat exact finisher counts — including numbers in older articles — as a snapshot, not a fixed fact. Field sizes move with entry caps, lottery demand, race-day weather, and shifts in regional participation, and a race that's near the top of this list one year may not be the next. Running USA and each race's own registration page are the most reliable sources for current field size, entry method, and pricing before you register or book travel.

Once you've picked a race, a solid training base matters more than which of these you choose — most half marathon training plans build toward 25 to 30 weekly miles, with one long run and two or three supporting runs during the week. If you haven't settled on a race yet, run through how to find a half marathon for a more systematic way to narrow the field.

Frequently Asked Questions

What is the largest half marathon in the United States?

The Indianapolis 500 Festival Mini-Marathon and the Brooklyn Half, organized by New York Road Runners, are consistently among the largest half marathons in the country by finisher count, though the exact ranking shifts year to year based on entry caps and demand. Both have decades of history and strong local participation cultures behind their size.

Do I need to enter a lottery for the biggest US half marathons?

Several do use lottery or qualifying-standard entry, including the United Airlines NYC Half and the Brooklyn Half, and New York Road Runners also runs guaranteed-entry programs for members who race and volunteer at NYRR events — the exact requirements differ by race and change over time, so check NYRR's current entry rules. Others, like the 500 Festival Mini-Marathon and the Rock 'n' Roll series races, are typically open registration until they sell out.

How far in advance should I register for a large US half marathon?

Register three to six months ahead for destination races like Walt Disney World or NYC Half, since both draw national fields and can sell out or fill lottery pools quickly. Regional races like the 500 Festival Mini-Marathon and Rock 'n' Roll Nashville are usually fine registering two to four months out, though earlier is always safer for a guaranteed spot and lower pricing.

Which large US half marathons are good for first-timers?

The 500 Festival Mini-Marathon and Rock 'n' Roll Nashville are both known for generous time cutoffs and strong crowd support, which makes them more forgiving for a first half marathon than a race with a strict pace requirement. Whichever race you pick, check the official time cutoff before you register if you're not yet confident about your finishing pace.