Colorado Rapids GM Padraig Smith says the club is proud to have sold Auston Trusty to Arsenal.
The young defender was signed by the Gunners on deadline day last month before being loaned back to the Rapids.
Smith, said it was a proud moment to see Trusty join a club of Arsenal's stature.
"Auston is coming off an exceptional season in 2021 in which he played a vital role in helping us finish atop the Western Conference for the first time in our history," he said.
"We remain committed to bringing through the top young players from Colorado and across the United States and to providing them with a platform to flourish, achieve success in MLS and earn the chance to make a move to Europe.
"Auston's outstanding performances caught the eye of several European clubs over the past 12 months and we are privileged to be part of an organisation with the reach and scale of KSE that allows us to help a player of Auston's potential further his development and career aspirations in Europe."