The 42nd Chicago Marathon is on Sunday, and more than 45,000 participants from around the world will be in town for the 26.2-mile race.

Here’s a rundown of things to know about how to get to the marathon, the best viewing spots, how the race works, who the top runners are and other details.

Where and when it’s happening

The race begins and ends in Grant Park on the city’s lakefront, and the course winds through 29 neighborhoods. The start line is at the intersection of Columbus and Monroe.

The event will last from about 7 a.m. to 3:30 p.m.

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What’s the route?

Here are the basic boundaries of the course: Grant Park on the east, Sheridan on the north, Damen on the west and 35th Street on the south.

This PDF includes a map.

What are some prime viewing spots?

Spectators will not have access to start and finish areas within Grant Park, but they can catch the participants at other critical moments during the race.

• Closest to the start: Grand between Columbus and State; or State between Grand and Jackson.

• Closest to the finish: Michigan and Roosevelt.

• On the North Side: Sheridan between Broadway and Lake Shore Drive.

• Halfway point (mile 13): Wacker and Wells.

• On the South Side: 35th Street between State and Indiana.

How do you launch 45,000 people in a race?

It definitely takes some organization and timing.

Start times begin at 7:20 a.m. for participants with disabilities and those using wheelchairs or handcycles.

Start times for runners are staggered by group:

• 7:30 a.m. Wave 1 (red)

• 8 a.m. Wave 2 (blue)

• 8:35 a.m. Wave 3 (orange)

The marathon has a time limit of 6 hours and 30 minutes. After that, the course reopens to traffic.

How will traffic be affected?

There will be a lot of street closures and no parking zones along the course on Sunday. Residents be warned: Towing of vehicles on the course will begin at 1 a.m. Sunday.

More details are on the marathon’s street closure notification web page.

How can I get there on mass transit?

The CTA will have extra service on many of its train lines, and some buses will be rerouted. The CTA website has details.

Metra will have additional trains on most of its lines, and it offers unlimited rides on Sunday with a $10 weekend pass. The Metra website has more info.

The South Shore Line, which connects northwest Indiana with Chicago, is also planning extra service. Check its South Shore Line website.

Will there be security checkpoints?

Anyone planning to enter Grant Park will have to pass through one of four security and bag-screening checkpoints located at:

• Monroe and South Lake Shore Drive

• Monroe and Michigan

• Jackson and Michigan

• Ida B. Wells and Michigan

Don’t bother bringing …

Non-registered wheelchairs, strollers, bicycles, skateboards, large bags, hard-sided coolers, costumes covering the face, bulky outfits, props, pets, alcohol, weapons and chairs.

Who are some top participants to watch?

Some of the world’s elite marathon athletes, including past winners of the Chicago Marathon, will be taking part.

Men’s field:

• Mo Farah: 2018 Chicago Marathon champion, four-time Olympic gold medalist

• Galen Rupp: 2017 Chicago Marathon champion, 2016 Olympic marathon bronze medalist

• Dickson Chumba: 2016 Chicago Marathon champion

• Lawrence Cherono: 2019 Boston Marathon champion

Women’s field:

• Brigid Kosgei: 2018 Chicago Marathon champion, 2019 London Marathon champion

• Jordan Hasay: U.S. marathon debut record holder

• Betsy Saina: 2018 Paris Marathon champion

• Emma Bates: 2018 USATF Women’s Marathon champion

Wheelchair field:

• Daniel Romanchuk: 2018 Chicago Marathon champion

• Manuela Schär: 2018 Chicago Marathon champion

• Aaron Pike: American record holder

• Susannah Scaroni: American record holder

What are the course records?

The Chicago Marathon is famous for being flat and fast. Here are the current records:

Men runners: 2 hours, 3 minutes, 45 seconds; Dennis Kimetto; Oct. 13, 2013

Women runners: 2 hours, 17 minutes, 18 seconds; Paula Radcliffe; October 13, 2002

Wheelchair men: 1 hour, 26 minutes, 56 seconds; Heinz Frei; Oct. 10, 2010

Wheelchair women: 1 hour, 39 seconds, 15 seconds; Tatyana McFadden; Oct. 8, 2017.

Thanks, but I’ll just watch it on TV

WMAQ-Ch. 5 and Telemundo Chicago will have live coverage from 7 a.m. to 11 a.m., and they’ll be streaming at nbcchicago.com and telemundochicago.com.

There will be live radio coverage on 670 The Score Sports Radio.

Minju Park is a news intern at WBEZ.