The United States Olympic Committee (USOC) held more than 400 events to mark Olympic Day with nearly 45,000 people claimed to have taken part across the country.
The LA84 Foundation held an event in Los Angeles, which will host the 2028 Olympic and Paralympic Games.
The event featured more than 11,000 students from 127 elementary and middle schools in the Los Angeles Unified School District.
Each of the schools received an activation package, including a welcome letter and LA84 and USOC Olympic Day banners.
They were also given instructions for a team handball sport experience.
The LA84 Foundation celebrated Olympic Day under the theme of "Move, Learn and Discover".
"We are proud to provide young Angelenos the chance to learn, take part in, and be inspired by Olympic Day and the values it supports," said Renata Simril, President and chief exuective of the LA84 Foundation.
"Every day is Olympic Day for the LA84 Foundation, and this opportunity will positively change the lives of the youth that we serve.
"The LA84 Foundation's goal, 'play for all', aims to get every child's life ready through sports, regardless of zip code."
The LA84 Foundation, a non-profit organisation, was created to manage the profits created by the 1984 Olympics in Los Angeles.
In total, events took place in nearly 200 communities across the US.
"Olympism is a way of life based on respect for human dignity." - Baron Pierre de Coubertin— LA 2028 (@LA2028) June 23, 2018
Happy #OlympicDay from #LA2028! Today we celebrate the power of sport to bring people together and highlight extraordinary human achievement. #UnitedBy pic.twitter.com/m7IJcvlvKg
"Olympic Day is an honoured tradition that brings together communities around the world to celebrate the values of Olympism," said Susanne Lyons, acting USOC chief executive.
"We are so proud of the hundreds of inspiring Team USA athletes, National Governing Bodies and Multi-Sport Organisations that help spread the power of sport and Olympic values to the next generation of Team USA athletes and fans."
The Colorado Springs Olympic Training Centre hosted a free event featuring a public tour, a meet and greet with athletes and a cauldron lighting ceremony conducted by Mayor John Suthers.
Earlier this month, 28 local students were honoured with the Olympic Ideals Award for exemplifying the Olympic values of excellence, friendship and respect.
The award was granted by Olympic City USA and the students were recognised with a special ceremony on June 11.
Olympic Day is held annually on June 23 to commemorate the birth of the modern Olympic Games in 1894.
It is aimed at encouraging fitness, well-being, culture and education, along with promoting the Olympic values of excellence, friendship and respect.
Olympic Day events in the US were supported by national governing bodies and more 50 Olympic, Paralympic, Pan American and Para-Pan American athletes.