The cub was born in August. She is the first panda to survive birth at the zoo since 2005.
Some people in the crowd drove hundreds of miles. They were apparently more excited than the 5-month-old Bao Bao, who fell asleep after a few minutes.
The National Zoo is extending its hours this weekend for the giant panda house. Visitors are allowed into the building in small groups to avoid overcrowding.
The zoo says the amount of time Bao Bao and panda mother Mei Xiang will be on exhibit each day depends on their behavior. They will have access to their private den, if they choose.
(The Associated Press contributed to this report)