The sweeping red-rock vistas at Utah's Zion National Park are increasingly filled with a bumper crop of visitors.
Now park managers are weighing an unusual step to manage the tide: Requiring tourists to make RSVPs to get in.
Authorities say it would be a first for the National Parks system. But with stagnant budgets and hours-long waits, it might be necessary.
A record 4.3 million people visited Zion last year. Park rangers say crowds are eroding soil, trampling plants and even cutting miles of their own trails.
Public comment on a Park Service proposal is open until mid-August.
