Travel National park reservation requirements return for summer 2023. See which parks require timed entry. April 21, 2023April 21, 2023 Eve Chen, USA TODAY Comments Off on National park reservation requirements return for summer 2023. See which parks require timed entry. Visitors hoping to experience Acadia's Cadillac Summit Road, Glacier's Going-to-the-Sun Road or Zion's Angels Landing this summer need to plan now.