Bruce Babbitt, the US Secretary of the Interior, marked the start of 1997 by announcing stricter limits on aircraft overflying the Grand Canyon in Arizona. Under the new rules, aeroplane and helicopter tours will be outlawed in 80 per cent of the airspace over the canyon, compared with 40 per cent previously. In the summer months, all flying will be barred before 8 am and after 6 pm.
The new controls are designed, however, as only the first phase in a longer-term plan to reverse the encroachments of all private vehicles in the canyon and other popular parks like Yellowstone and Yosemite. At the canyon, for example, proposals already approved will eventually force visitors to leave their cars outside the park and take shuttle buses to points inside.
"At peak periods of summer overflights, the south rim of the Grand Canyon is noisier than Times Square on New Year's Eve," Mr Babbitt said as he announced the flight limits. Underlining the dawn and dusk plane curfews, he added: "These are the truly magical hours in the Grand Canyon".
The entire park system, meanwhile, should be considerably fortified by the increase in entrance fees approved by the US Congress last year. Due to take effect this month, the changes will mean for instance a doubling from $10 to $20 of the entrance charge for one car into the canyon this summer.
The change in rates will especially benefit the largest parks which have been trying to reconcile falling federal contributions with rapidly rising visitor volumes. Yellowstone drew international attention to the issue last summer when it closed down some of its areas to tourists, pleading penury.
By addressing motorised traffic, meanwhile, the government is getting into the central dilemma of the park system's management: at what point does the need to protect America's wonders become more important than the principle of keeping them accessible to all?
The plan gradually to expel private cars from the Grand Canyon will be put into motion this year and phased in over 15 years. If all goes well, from 2012 no more will be allowed entry.
"In some ways this says `no more, we are not going to remain slaves to the automobile', as we have been," Ron Arnberger, the superintendent of the Grand Canyon, said.