WAPITI, Wyo. — Several thousand cars, trucks and recreational vehicles were backed up in long lines at entrances to Yellowstone National Park as it partially reopened Wednesday following record floods that reshaped the park’s rivers and canyons, wiped out numerous roads and left some areas famous for their wildlife inaccessible, possibly for months to come.

Park managers opened three of Yellowstone’s five entrances for the first time since June 13, when 10,000 visitors were ordered out after rivers across northern Wyoming and southern Montana surged over their banks following a torrent of rainfall that accelerated the spring snowmelt. The cost and scope of the damage is still being assessed, Yellowstone Superintendent Cam Sholly said Wednesday.

Some of the premier attractions at America’s first national park will again be viewable, including Old Faithful. But the bears, wolves and bison that roam the wild Lamar Valley and the thermal features around Mammoth Hot Springs will remain out of reach.

The wildlife-rich northern half of the park will be shuttered until at least early July, and key routes into the park remain severed near the Montana tourist towns of Gardiner, Red Lodge and Cooke City.

To keep visitor numbers down while repairs continue, park managers will use a system that only allows cars with even-numbered last digits on their license plates to enter on even days, while vehicles with odd-numbered last numbers can come on odd days.

Groups of visitors traveling together in different cars are exempt from the license plate system as well as people with reservations at campgrounds and hotels in the park.