Bureau of Land Management officials say the festival's peak attendance was 52,385 on Friday, down 1.7 percent from a year ago.
The agency established a daily cap of 60,900 for this year's gathering, which ends Monday.
The BLM placed organizers on probation and threatened to pull their license for exceeding the attendance cap at last year's festival.
The offbeat fest drew daily crowds of more than 53,000 to the Black Rock Desert on both Sept. 2 and 3 last year. A daily cap of 50,000 was allowed then under terms of its special recreation permit.
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