With just over a month away, the 45th annual Bank of American Chicago Marathon for 2023 will be one of the most special yet, as one participant on Oct. 8 will help the race reach a major milestone.

According to organizers, the Chicago Marathon began in 1977, with its first location at Buckingham Fountain to Lincoln Park. Since then, more than 960,000 participants have crossed the finish line.

This year, the race will see its millionth finisher.

"On Sunday, October 8, we will welcome the millionth finisher across the line in Grant Park," a letter to participants from Carey Pinkowski, Executive Race Director read. "While being the millionth finisher is a unique honor, it took 999,999 finishes to reach that milestone: finishes made up of world records, American records and personal records, of smiles, tears and disbelief, of pride, pain and awe."

"Whether you’ve contributed to that number by running a past Chicago Marathon or will contribute to that number this fall, you are a significant part of the race’s story," the letter continued.

Earlier this year, the marathon's 2023 elite field was announced, a lineup of athletes organizers are calling "one of the deepest, most-decorated assemblies of athletes in race history."

This year's race will see all four of its defending champions return to city streets on Oct. 8, with a number of records at risk.

“Chicago has been home to world-records, historic debuts and has served as an introduction to runners who became legends of the sport,” Executive Race Director Carey Pinkowski said in a statement. “As we prepare to celebrate a landmark year in the race’s history, we anticipate historic performances that we will talk about for years to come.”

Elite athletes participating in the Bank of America Chicago Marathon for 2023

Among the notable names are 2022 men's champion Benson Kipruto, women's champ Ruth Chepngetich, men's wheelchair winner Marcel Hug and women's wheelchair winner Susannah Scaroni.

Kipruto broke away in the 25th mile last year to win with the fourth fastest time ever in Chicago. If he wins again, he will be the first back-to-back men’s open field champion since Sammy Wanjiru in 2010.

But he'll be lining up against the second-fastest man in history.

Fellow Kenyan Kelvin Kiptum, who won the 2023 London Marathon in what was only his second-ever marathon race and nearly broke a world record, will make his U.S. marathon debut in Chicago. In addition, Olympic medalist Bashir Abdi, 2021 Chicago winner Seifu Tura, Olympic hopeful and American leader Connor Mantz and 2017 champion and the only American to win the race in the last 20 years, Galen Rupp.

In the men's wheelchair race, Hug will return to defend his title and course record, but he'll be battling three-time Chicago champion Daniel Romanchuk, along with other elite racers Aaron Pike, Sho Watanbe, five-time Chicago winner Ernst Van Dyk and Jetze Plat, who will make his Chicago debut.

Organizers had previously announced an exciting women's field that will see legendary matchups and the potential for history to be made.

Chepngetich and American record holder Emily Sisson will both make their returns to the Chicago event. Meanwhile, 2023 London Marathon champion Sifan Hassan, one of the most accomplished distance running stars, will make her American debut.

Chepngetich of Kenya ran the second-fastest time ever in the Chicago race last year, narrowly missing a world record as she fell just 14 seconds behind Brigid Kosgei's 2019 finish. This year, she'll be seeking her third consecutive win, and a another chance at a women's world record.

“I am planning to defend my title and improve my time,” Chepngetich said in a statement. “There's no better race in the world than the Bank of America Chicago Marathon.”

But Hassan could throw a curveball into the race, as the two-time Olympic gold medalist and three-time world champion from the Netherlands joins the mix. Hassan made her marathon debut in London last April and won with a national record, despite stopping twice to stretch.

Sisson, 2022's runner-up who demolished the American record by 43 seconds, is also expected to be a force in the race and hopes to run even faster this year.

“Chicago is where I set the American marathon record last year,” Sisson said in a statement. “I am really looking forward to coming back for another great race in October."

Joining the previously-announced women's field are 2021 London winner Joyciline Jepkosgei and one of the most decorated athletes of all-time, Genzebe Dibaba of Ethiopia, both of whom are making their Chicago debuts.

In the women's wheelchair race, Scaroni will face two of the greatest competitors of all-time: nine-time Chicago champ Tatyana McFadden and two-time Chicago champion Manuela Schär, who withdrew from last year's race and will be going for her third win.

A total of 45,000 runners are set to hit Chicago streets for the 2023 Chicago Marathon this year. The race is slated to take place on Oct. 8.

Here's a look at the full lineup:

Bank of America Chicago Marathon Elite Field – Men’s Open Division
Name Country Personal Best
Kelvin Kiptum KEN 2:01:25 (London, 2023)
Bashir Abdi BEL 2:03:36 (Rotterdam, 2021)
Benson Kipruto KEN 2:04:24 (Chicago, 2022)
Dawit Wolde ETH 2:04:27 (Rotterdam, 2021)
Seifu Tura ETH 2:04:29 (Milan, 2021)
Daniel Do Nascimento BRA 2:04:51 (Seoul, 2022)
John Korir KEN 2:05:01 (Chicago, 2022)
Galen Rupp USA 2:06:07 (Prague, 2018)
Huseydin Mohamed ETH 2:05:05 (Amsterdam, 2022)
Milkesa Mengesha ETH 2:05:29 (Valencia, 2022)
Conner Mantz USA 2:08:16 (Chicago, 2022)
Yuki Matsumura JPN 2:09:01 (Otsu, 2021)
Takashi Ichida JPN 2:09:15 (Oita, 2022)
Kei Katanishi JPN 2:09:27 (Otsu, 2021)
Masashi Nonaka JPN 2:09:47 (Osaka, 2023)
Matt McDonald USA 2:09:49 (Chicago, 2022)
Mick Iacofano USA 2:09:55 (Chandler, 2020)
Masaki Tuda JPN 2:10:40 (Oita, 2023)
Mizuki Higashi JPN 2:11:04 (Tokyo, 2023)
Colin Mickow USA 2:11:22 (Chandler, 2020)
Frank Lara USA 2:11:32 (Houston, 2022)
Dan Kremske USA 2:14:53 (Chicago 2019)
Daniel Mateiko KEN Debut
Wesley Kiptoo KEN Debut

Bank of America Chicago Marathon Elite Field – Men’s Wheelchair Division
Name Country Personal Best
Marcel Hug SUI 1:17:47 (Oita, 2021) World Record
Ernst Van Dyk RSA 1:18:04 (Boston, 2017)
Aaron Pike USA 1:20:02 (Duluth, 2022)
Johnboy Smith GBR 1:20:05 (Duluth, 2022)
Kota Hokinoue JPN 1:20:54 (Seoul, 2013)
Daniel Romanchuk USA 1:21:36 (Boston, 2019)
Rafael Botello ESP 1:22:09 (Boston, 2017)
Jordi Madera ESP 1:22:10 (Boston, 2017)
Patrick Monahan IRL 1:22:23 (Duluth, 2019)
Sho Watanabe JPN 1:24:00 (Oita, 2019)
James Senbeta USA 1:24:27 (Boston, 2017)
Simon Lawson GBR 1:25:06 (Boston, 2017)
Jetze Plat NED 1:28:44 (London, 2023)

Bank of America Chicago Marathon Elite Field – Women’s Open Division
Name Country Personal Best
Ruth Chepngetich KEN 2:14:18 (Chicago, 2022)
Joyciline Jepkosgei KEN 2:17:43 (London, 2021)
Genzebe Dibaba ETH 2:18:05 (Amsterdam, 2022)
Sutume Kebede ETH 2:18:12 (Seoul, 2022)
Emily Sisson USA 2:18:29 (Chicago, 2022)
Sifan Hassan NED 2:18:33 (London, 2023)
Tigist Girma ETH 2:18:52 (Valencia, 2022)
Ababel Yesheneh Eth 2:20:51 (Chicago, 2019)
Des Linden USA 2:22:38 (Boston, 2011)
Emma Bates USA 2:23:18 (Eugene, 2022)
Aliphine Tuliamuk USA 2:24:37 (Boston, 2023)
Nell Rojas USA 2:24:51 (Boston, 2023)
Molly Seidel USA 2:24:42 (New York, 2021)
Dakotah Lindwurm USA 2:25:01 (Duluth, 2022)
Sara Vaughn USA 2:26:23 (Chicago, 2022)
Gabriella Rooker USA 2:27:38 (Duluth, 2023)
Diane Nukuri USA 2:27:50 (London, 2015)
Maggie Montoya USA 2:28:07 (Chicago, 2022)
Stacy Ndiwa KEN 2:31:53 (Istanbul, 2022)

Bank of America Chicago Marathon Elite Field – Women’s Wheelchair Division
Name Country Personal Best
Manuela Schär SUI 1:28:17 (Boston, 2017)
Susannah Scaroni USA 1:27:31 (Duluth, 2022)
Tatyana McFadden USA 1:31:30 (Duluth, 2019)
Jenna Fesemyer USA 1:33:50 (Duluth, 2022)
Catherine Debrunner SUI 1:36:47 (Berlin, 2022)
Vanessa De Souza BRA 1:40:21 (Seville, 2020)
Merle Menje GER 1:42:12 (New York, 2022)
Michelle Wheeler USA 1:45:45 (Oita, 2019)