Same destination, new goals: The Bank of America Chicago Marathon is back.

More than 45,000 runners will dash through Chicago Sunday with their eyes on the finish line at Columbus Drive. Organizers say the 42nd annual event again will welcome thousands of runners from all 50 states and more than 100 countries.

Many will bring an entourage: An estimated 1.7 million spectators are expected to line the course that stretches through 29 neighborhoods and begins and ends downtown.

Whether you’ve been carbo-loading for the race (or just for fun), if you’re anywhere in the city on Sunday, it’s likely you’ll be affected by the event. Here’s what you need to know about the Chicago Marathon:

When and where

The Bank of America Chicago Marathon begins at 7:30 a.m. Sunday in Grant Park, and runners will finish on the south side of the park.

How to get there

CTA buses and L lines that serve the Loop on Sundays (Blue, Green, Pink, Red, Brown and Orange) offer an easy way to get to Grant Park from across the city. The CTA provides updated travel information on its website.

Metra will add inbound and outbound trains on race day. Click here for a detailed schedule.

Whether you’re commuting to the race or elsewhere in the Loop, expect worse congestion and potential delays.

Road closing

Mre than 40 streets will be closed starting at 7 a.m. Sunday. They’re scheduled to be reopened between 10 a.m. and 6 p.m. The Chicago Marathon website lists which streets will be closed.

Security

A color-coded alert system will be used to communicate course conditions to the public. The levels will range from low to extreme, based primarily on weather, as well as other conditions.

Weather forecast

Sunday is expected to be mostly sunny, with a high of 53, according to the National Weather Service.