What’s New?

This year, for the 41st running of the city’s marathon, there’s a rare tweak to the route: To keep from blocking Ashland, runners will turn south onto Loomis from Taylor (A), just past the 18-mile marker. The half-mile difference will be made up with small diversions in other spots.

The route

Unlike the relatively straight courses of the Boston and Los Angeles marathons, ours is more like a five-legged beast that loops back on itself in several spots. It may be tempting to cheat where only one block separates the course (B), such as at La Salle and Wells or Jackson and Adams, but forget it: The microchips in runners’ bib numbers that accurately record finish times also ensure they run every step of the race.

Who to look for

• Brit Mo Farah, a four-time Olympic gold medalist and six-time world champion

• Galen Rupp, who won here last year (and was the first U.S. man to win since 2002)

• Jordan Hasay, whose 2017 time is the fastest ever by an American woman on U.S. soil

• Comedian (and fitness zealot) Kevin Hart, who ran the NYC marathon last year

Where to watch if …

You’re an agoraphobe (C):

Stay clear of Boystown, where it gets crowded (and crazy fun). Instead, hang out in the West Loop along Adams or Jackson.

You want to high-five your runner friends as often as possible:

Begin at the starting line on Monroe (D1)

Walk to Jackson and State (15 mins.) (D2)

Train to Sheridan and Broadway (30 mins.) (D3)

Train to Franklin and Monroe (40 mins.) (D4)

Train to Cermak and Wentworth (15 mins.) (D5)

Train to Michigan and Roosevelt (10 mins.) (D6)

You want to give support where it’s needed most (E):

Typically, competitors hit the wall around the 20th mile, near 18th and Halsted in Pilsen.

You like a grand finale (F):

Chill at the finish line, of course. In the race’s first year, 2,128 contestants made it to the end; last year, that figure ballooned to 44,341. Maybe you’ll witness history, like in 2007, when Patrick Ivuti beat two-time world champion Jaouad Gharib by five-hundredths of a second, the narrowest margin of victory ever at Chicago Marathon. Or maybe this is the year that someone beats the course record (2:03:45) set by Dennis Kimetto in 2013.

What you’ll hear

About 20 DJs will perform at aid stations scattered along the course. WXRT will curate music for the finish line (so the Pretenders, the Who, and Talking Heads are good bets). In case you forget what you’re doing, songs like “Born to Run” and “Sweet Home Chicago” will play on a loop at the starting line to jog (sorry) your memory.