All swimmers taking part were checked to make sure they could complete the course.

They included Olympic swimmer Olivia Smoliga, originally from Chicago, who won gold in Rio 2016 and bronze in Tokyo 2020.

She came first in the women’s one-mile race with a time of 22:45.

Doug McConnell, a Chicago local and co-founder of the event, had been asking the city’s leaders for more than a decade to allow a swim in the river, the first such event since 1927.

He was inspired by similar clean-ups of famous rivers in cities such as Paris, Munich and Amsterdam: “Seeing that really planted a seed, and we are thrilled we are finally doing this and that it has got global attention – we had applications across the US and 13 countries,”

He now hopes this will become an annual event and spread to other US cities.

“This is more than just a race, it’s a tribute to the river’s revival and a commitment to funding research and education that changes lives,” added Doug.

The event raised a total of $150,000 (over £110,000) for ALS research.