The National Museum of African American History and Culture, which opened in 2016, will allow visitors to enter without passes on weekdays in September. (Jahi Chikwendiu/The Washington Post)

It appears the end is in sight for timed passes to Washington’s hottest museum.

Two years after its star-studded opening, the National Museum of African American History and Culture will not require timed passes for visitors on weekdays in September. The month-long reprieve serves as a test for the future, officials said.

Weekend visitors will still need to have the free timed passes.

The museum has welcomed 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.”

Attendance on Wednesdays in April averaged 8,550 visitors, according to the Smithsonian, significantly higher than the average Tuesday attendance that month.

Hernandez said the museum will analyze the visitor data from September before making a permanent decision. The museum welcomed 733,000 visitors over 3 1/2 months in 2016, and 2.4 million in 2017. It will probably exceed that figure this year.

Wednesday’s online distribution of free, timed passes for October revealed signs that the crush for admission may have crested. Weekends were snapped up quickly, but it took all day for the rest of the passes to be claimed. In the first few months after the museum opened, all passes were claimed within minutes. (The museum’s normal distribution day on the first Wednesday of the month was pushed back by the Fourth of July holiday, which may have led to diminished demand.)

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.”