More than 2 million people visit Mount Rainier National Park each year to experience the majesty of nature by hiking, camping, picnicking, skiing, and joining guided interpretive programs. Park roads are narrow and winding, with maximum speeds of 35 mph in most places, and you have to watch for pedestrians, cyclists, and wildlife. Parking can be very difficult to find during the peak summer season, especially at Paradise, Sunrise, the Grove of Patriarchs, and at the trailheads between Longmire and Paradise; it's best to arrive early in the day if you plan to visit these sites.
The major roads that reach Mount Rainier National Park—highways 410, 706, and 123—are paved and well-maintained state highways. The Nisqually entrance is on Highway 706, 14 mi east of Route 7; the Ohanapecosh entrance is on Route 123, 5 mi north of U.S. 12; and the White River entrance is on Route 410, 3 mi north of the Chinook and Cayuse passes.
As these highways reach Rainier, they become mountain roads and wind up and down many steep slopes—cautious driving is essential. Vehicles hauling large loads should gear down, especially on downhill sections. Even drivers of passenger cars should take care not to overheat brakes by constant use. Because they traverse the shoulders of a mountain with tempestuous weather, these roads are subject to storms any time of year—even in midsummer—and are almost always being repaired in summer from winter damage and washouts. Expect to encounter road-work delays several times if you are circumnavigating the mountain.
The side roads that wind their way into the park's western slope are all narrower, unpaved, and subject to frequent flooding and washouts. All but Carbon River Road and Highway 706 to Paradise are closed by snow in winter. During this time, however, Carbon River Road tends to flood near the park boundary. (Route 410 is open to the Crystal Mountain access road entrance.) Cayuse Pass usually opens in late April; the Westside Road, Paradise Valley Road, and Stevens Canyon Road usually open in May; Chinook Pass, Mowich Lake Road, and White River Road open in late May; and Sunrise Road opens in late June. All these dates are subject to weather fluctuations.
All off-road vehicle use—4x4 vehicles, ATVs, motorcycles, snowmobiles—is prohibited in Mount Rainier National Park.