There are hundreds of sites to pitch a tent or park an RV within Mount Rainier National Park’s  campgrounds (800/365-2267, www.recreation.gov ), all with running water and flush or pit toilets but no RV hookups. Coin-op showers are available at the Paradise Visitor Center when it is open, but you’ll need to head to Ashford  or other towns for laundry facilities. Gathering firewood is prohibited in the park, but it can be purchased at the Cougar Rock and Ohanapecosh campgrounds, as well as the Longmire General Store.
Currently only three of the five major park campgrounds are fully operational; Sunshine Point Campground (near the Nisqually entrance) is closed due to damage sustained from flooding in 2006 and Ipsut Creek Campground (at the end of the Carbon River Rd. in the northwest corner, $8) is only accessible to walk-in campers due to the washout of Carbon River Road in the same storm surge. A filter is a must here, as there is no running water.
Easier places to stake the tent or roll up the camper are Cougar Rock Campground (2.5 miles northeast of Longmire, $12–15) or Ohanapecosh Campground (near the southeast entrance on Highway 123, $12–15). Both are open late May to mid-October and can accommodate RVs up to 32 feet. Reservations are highly recommended from July 1 to Labor Day at these two grounds.
Those making the sojourn up to Sunrise and hikers planning on bivouacking up at Camp Schurman before an Emmons Glacier attempt like to stop in at White River Campground (on the east side in the Sunrise area, open late June– late Sept., $12).
The road is bumpy leading to the free Mowich Lake Campground (open mid-July–mid-Nov.) walk-in sites, the facilities are primitive, and there’s no running water. But you’ll be rewarded for your trouble by smaller crowds and pretty lakefront spots. Camping is not permitted in the Paradise area or along park roads in the summer, but winter camping is allowed at Paradise once the snow depth tops five feet. Get permits and details on locating your camp from the visitors center.