The U.S. Department of Defense says the Taliban have stopped Afghans from going to Kabul airport because of the crowds.
A Pentagon spokesman said 21,600 people had been evacuated from Kabul in 24 hours.
He said the United States had resettled 63,900 people since late July.
According to the US Department of Defense, there is currently no change in the withdrawal from Afghanistan until August 31.
The spokesman said the United States has the capability to repatriate all Americans in Afghanistan.