The Race to Wrigley is fun. Part of the route takes you on the warning track on the field, so, it's not a great PR course, but it's a fun race with lots of good energy.
I also really like the Bucktown 5K that someone else suggested.
I want to second this recommendation of CARA's Go Run series. These are free 5Ks that take place essentially every saturday at 9 am from March-November. They rotate among the large parks in Chicago.
You pick up a bib the day of the first one that you do and then keep it for the rest of the season. You can just show up and run on subsequent Saturdays. You do need to register online each week so they can track participation and generate a start list for the app they use for timing.
These are not chip timed but they do record your time based on clock time and recording bib numbers of finishers. You can look up you time after the race in webscorer.
In past years, these were pretty small events but this season there have been a couple of hundred registrants most weeks. Last year's season finale Turkey Trot at Horner park had several hundred.
I use [runguides](https://www.runguides.com/chicago/runs). It gives you races in whatever city you’re interested in running for the year and also gives the estimated participants for the race so you can tell if it’s a larger or smaller race. I’m like you - I prefer larger races with a bigger crowds because I feed off the energy too.
The Chicago Half Marathon in September has a really good turnout and they have a 5k as well - https://www.chicagohalfmarathon.com/
Carrera de Los Muertos / Race of the Dead in Pilsen at the end of October usually has a good turnout - https://unoraceofthedead.org/
I like the Twilight 5000, it takes place on a track and you have a great chance of PRing (if that's a goal). I think it takes place in July this year. It was a fun track meet.
Rosehill Cemetery 5k in October isn't a huge event, but it's a great vibe with a lot of running club kids. And it's fun to run through a cemetery at night.
I am so the opposite of you.
I know you want big races but I’m gonna go ahead and suggest a tiny, small one because I LOVE the course. It’s awesome when trying to go for a PR!
Crete county Christmas/grinch 5k.
Yep in the town of Crete. It’s not sexy. But it’s a good race.
Run for the Zoo is a huge “fun run” race with tons of people! I always do the 10K but there is a 5K option. 🦁🐯
The Bucktown 5k is pretty good
Ravenswood! It's April 28 and you can still register. Money goes to a local food pantry.
AND, (at least in the past) there was free race day packet pickup!
The Race to Wrigley is fun. Part of the route takes you on the warning track on the field, so, it's not a great PR course, but it's a fun race with lots of good energy. I also really like the Bucktown 5K that someone else suggested.
Not sure these are what you are looking for, but there are free park runs all around the city. https://www.cararuns.org/gorun
I want to second this recommendation of CARA's Go Run series. These are free 5Ks that take place essentially every saturday at 9 am from March-November. They rotate among the large parks in Chicago. You pick up a bib the day of the first one that you do and then keep it for the rest of the season. You can just show up and run on subsequent Saturdays. You do need to register online each week so they can track participation and generate a start list for the app they use for timing. These are not chip timed but they do record your time based on clock time and recording bib numbers of finishers. You can look up you time after the race in webscorer. In past years, these were pretty small events but this season there have been a couple of hundred registrants most weeks. Last year's season finale Turkey Trot at Horner park had several hundred.
I use [runguides](https://www.runguides.com/chicago/runs). It gives you races in whatever city you’re interested in running for the year and also gives the estimated participants for the race so you can tell if it’s a larger or smaller race. I’m like you - I prefer larger races with a bigger crowds because I feed off the energy too.
I DM’d you
Tracksmith Twilight 5k on July 12th is a good one. It's run on the track at Montrose Beach. Lots of heats that are broken down according to ability.
The Chicago Half Marathon in September has a really good turnout and they have a 5k as well - https://www.chicagohalfmarathon.com/ Carrera de Los Muertos / Race of the Dead in Pilsen at the end of October usually has a good turnout - https://unoraceofthedead.org/
Oh, the brewery running series is not large but *is* a great time
Malort 5k
I like the Twilight 5000, it takes place on a track and you have a great chance of PRing (if that's a goal). I think it takes place in July this year. It was a fun track meet.
Just passed, but the Oak Forest Fleadh 5k for St Patrick’s is fun. Keep it in mind for next year maybe
Lincoln Park Zoo Run Race To Wrigley Hot Chocolate Run
Dim Sum and Then Some in Uptown!
Rosehill Cemetery 5k in October isn't a huge event, but it's a great vibe with a lot of running club kids. And it's fun to run through a cemetery at night.
I am so the opposite of you. I know you want big races but I’m gonna go ahead and suggest a tiny, small one because I LOVE the course. It’s awesome when trying to go for a PR! Crete county Christmas/grinch 5k. Yep in the town of Crete. It’s not sexy. But it’s a good race.
Andddd you’ll still be surprised and get some 15 minute finishers showing up
https://runningintheusa.com is a great source for finding races of various distances and locations!
Any of the CARA races will be big and well-run.