Zion National Park in Utah yesterday became the first national park in the lower 48 states to ban automobiles from its most popular area. The National Park Service launched a shuttle-bus system that requires most visitors to leave their vehicles at the park entrance; people are also encouraged to bicycle and walk in the park. The park service came up with the plan as a way to cut down on congestion, noise, and pollution from the cars, motor homes, and tour buses that were transporting the park’s 2.5 million annual visitors. “I think it would be safe to say that in 10 or 20 years a number of parks may have systems” like this, said park service spokesperson Carol Anthony.