Park visitation for January through May was 317,882, down 11.4 percent from the same five month period last year. Visitation for the month of May was 218,317, down 12.8 percent from May 2010 levels.
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Yellowstone Visitation
| Month | 2011 | 2010 | Change |
| January | 24,517 | 25,595 | -4.2 |
| February | 28,174 | 29,108 | -3.2 |
| March | 18,728 | 21,028 | -10.9 |
| April | 28,147 | 32,763 | -4.1 |
| May | 218,317 | 250,445 | -12.8 |
| Year-To-Date | 317,882 | 358,939 | -11.4 |
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Most of the park is inaccessible by automobile during the winter and early spring. May represents the first month most major park roads are typically open to wheeled visitor traffic, and when visitor services begin to reopen for the busy summer season.
The winter and spring seasons represent a small but important portion of the park's annual visitation.
In comparison, as many people typically visit the park during the first two weeks in July as entered the park during the entire first five months of this year.
The park has experienced back-to-back record visitation years, with nearly 3.3 million visitors in 2009 and over 3.6 million visitors in 2010.
