National Parks will ONLY upgrade entrance or use receipts from National Parks to an Annual Pass, and will NOT UPGRADE entrance or use receipts from other land management agencies. Any upgrades must be done IN PERSON AT A NATIONAL PARK, within 7 days of the original entry receipt purchase date.
去美国国家公园,不都是直接买年票的么?
一个公园20美金,一年年票全包才80美金……