Crowd estimates for Jan. 20 range between 1 and 5 million people.

Metro is planning to carry upwards of 1 million riders itself on Inauguration Day, but the transit agency says it will shut down all of its public restrooms due to security concerns.

Instead, 146 portable restrooms will be set up outside of selected rail stations.

Even if the transit agency carries 1 million people on Jan. 20 -- and that could be a conservative estimate -- that means there would be one bathroom for every 6,849 customers.