Major League Soccer lost almost $1bn (£750m) in revenue during 2020 because of the coronavirus pandemic.
MLS was only two weeks into its historic 25th season when a halt was called to the campaign in March.
It did not resume until July, with the MLS is Back competition in Florida, before a revised regular schedule ran from 12 August.
“The overall [financial] impact is going to be deeper than we expected,” said MLS commissioner Don Garber.
With the three Canadian teams forced to play all their matches in the United States and Columbus Crew only able to admit a crowd of 1,500 when they host Seattle Sounders in the MLS Cup final on Sunday, the financial effects of the season will be felt for a long time
“Revenue for the league and its clubs is down almost $1bn compared to last year,” added Garber.
“But we also incurred expenses we were not intending to occur, including charter planes for the teams and creating the whole bubble around MLS is Back.”