This post was updated on Aug. 31.

Weekday visitors will not need passes to enter the Washington’s hottest museum next month.

Starting Monday and continuing through September, the National Museum of African American History and Culture will waive the requirement for timed passes weekday hours. The month-long reprieve serves as a test for the future, officials said.

Weekend visitors will still need the free passes because the crowds are so large.

The museum has had more than 4.5 million visitors since it opened on Sept. 24, 2016, including 1.5 million in the first half of this year.  The passes — distributed online in advance and for same-day use — have been used to limit lines to enter, control crowds in the galleries and provide a better museum experience.

The September pilot is the most dramatic step in the museum’s long-standing effort to move away from passes. Months after opening, it began admitting a small number of walk-up visitors after 1 p.m. Officials first tested all-day no-pass entry on Wednesdays in April and May, and were pleased with the increased number of visitors, said Shrita Hernandez, the museum’s chief communications officer.

“We want to test it for a longer time,” Hernandez said, “with the idea of being like other Smithsonian museums on the Mall,” which do not require passes to enter. “We want to make sure people have the easiest access to the museum as possible.”

The museum will analyze the visitor data from the September experiment before making the decision to permanently do away with passes, Hernandez said.

The museum had 733,000 visitors over three and a half months in 2016, and 2.4 million in 2017. It will probably exceed that figure this year. Before opening, museum officials expected to have 3 to 4 million visitors each year.

Hernandez said the museum selected September for its month-long trial because students will be back at school and tourism will be down.

“It is traditionally not the peak season for Smithsonian institutions,” she said. “We thought it would be a good time to get some good data to see how we proceed.”