This is the most popular and crowded route to the summit in the summer. The first 2.1 miles of the trail are a hike through forests. When you cross Loowit Trail there is a toilet on the right. After this the trail follows the rocky ridge and is marked by large wooden posts almost to the summit. You'll pass a couple tripod monitors on the ridge that give it its name. After the last post, just follow the ridge to the summit. In the summer, it's a dusty crowded hike. In the winter, you'll want crampons and an ice axe or be sure-handed with some trekking poles.
From I-5, take exit 21 for Woodland, WA. Drive east following signs for Cougar, WA. About 25-30 miles down the road, you need to register at Jack's Restaurant (see the Main Page for details in summer, for winter climbing which is Nov 1 - Mar 30 there is no fee, you just need to register). About 6 or 7 miles past Jack's is the town of Cougar and just a few miles past Cougar is the turnoff for Climbers Bivouac Road 83. Turn left there and follow signs for Climbers Bivouac. You'll go just over 3 miles on Road 83, take a left on Road 8100 and go about a mile and a half, then take a right on gravel road 830 for about 2.5 to 3 miles to the turnaround. The trail starts just next to a small shed/restrooms at the turnaround.