There are several access points to the Wonderland Trail. The main entry points for Mount Rainier National Park are each possible starting points for the Wonderland, too.
Carbon River (Pin Dropped at this entrance)
From Buckley, head south on Highway 165 for 1.6 miles. Turn left and stay on Highway 165, passing Wilkeson and crossing the the Carbon River Bridge before turning left toward Carbon River at 10.3 miles. Continue another 7.7 miles to the end of the road at Mount Rainier National Park, 18 miles from Buckley.
Parking for a dozen vehicles. Indoor toilets on the river side, opposite the Rainforest Loop trail. Carbon Glacier Trail starts after hiking or biking the 5 miles of abandoned Carbon River Road to Ipsut Creek Campground and then 3.5 miles along the Carbon Glacier Trail. Toilets, information board, and bike rails at trailhead.
From I-5, take exit 143 for S 320th St toward Federal Way. Stay in the left 2 lanes to turn left onto S 320th and proceed for 0.8 miles. Turn right onto Military Road S and drive for 4.4 miles, then turn left onto WA-161 S and proceed for 3.9 miles.
Get into the two left-hand lanes, and turn left onto WA-167 N toward WA 410, then take the exit for 512 W toward 161 S. Proceed on 512 W for 2.5 miles, then exit for South Hill. Follow the signs for 161S/Eatonville/Mount Rainier.
Stay on 161 S for 22.6 miles, then turn left onto Center St. E, into Eatonville. Continue onto Alder Cutoff Road E for 6.5 miles, then at a 'T' intersection, turn left onto WA-7 S. Drive through the tiny town of Elbe and continue along Hwy 706, which becomes the Paradise Road when you enter the park. Longmire is about 25 miles from the 'T' intersection before Elbe.
From Longmire, continue up the Paradise Road to the large parking area and the Henry M. Jackson Visitors Center.
From the east, take Highway 123 to Stevens Canyon Road (Note that this road is closed in the winter). 19 miles from the turnoff, turn right onto Paradise Road East. Continue two miles to the Paradise Visitors Center.
From Enumclaw, follow SR 410 east for 43 miles until you reach Sunrise Park Rd/White River Rd. Make a slight right at the fork and follow along for 5 miles and over the White River. The road then switchbacks to become exclusively Sunrise River Rd and continues 10 miles to its end at the Sunrise Visitor Center and the parking area.