These are the Park Service's own visit counts for every unit, going back to 1979. You can run the ranking one year at a time, put several parks on the same chart, see which months a park is busy, and look at how 2020 went at the largest ones.
These are recreation visits as the Park Service counts them: entries at gates and traffic counters, not people. A commuter on a parkway counts every morning. Units report on their own schedules, and a year with a missing month is left blank rather than guessed. New units appear when their counting starts. Sequoia and Kings Canyon report as one.
Source: National Park Service Visitor Use Statistics, monthly recreation visits by unit, 1979 to 2025, via the IRMA stats service. Names and designations from the Park Atlas open data file (CC0). Data refreshed .
Every unit ranked by 2025 visits on Park Atlas · Every unit, every visit, the Labs board with fees and dark skies · The Park Atlas guides