A boulder fell onto Highway 140 about 11 a.m. Thursday, blocking traffic from entering or leaving Yosemite National Park along that route, park officials said. No one was hurt.
The rock fell about half a mile east of Yosemite View Lodge in El Portal, just inside the park boundary.
Park officials said the boulder is an estimated 10 to 15 feet high, six feet wide and four feet deep.
The park said the road will remain closed at that spot for at least 24 hours while crews assess the area and remove any obstacles and tend to other safety concerns.
Highway 140 leads into one of three gates to the park on its western side. The other gates -- via Highway 120 to the north and Highway 41 to the south -- remain open.
A 2006 rock slide east of the town of Mariposa closed Highway 140 and blocked access to the park for many months.
For road information at the park, call 209-372-0200.