Twenty miles west of Mossyrock  on Highway 12 and just three miles east from I-5 is the crossroads called Marys Corner. Just south of the intersection on Jackson Highway is the John R. Jackson House, a log cabin built in 1845 that was a popular stopping place for Oregon Trail travelers. Jackson was one of the first American settlers north of the Columbia River, and this building served as the first U.S. District Court in what would become the state of Washington. Just north of Marys Corner on Jackson Road is a monument to John Jackson’s wife, Matilda. (Technically, this five-acre plot of land is Matilda N. Jackson State Park.)
Two miles south of Marys Corner, the road passes Lewis and Clark State Park (360/864-2643), which preserves a proudly standing grove of old-growth evergreen. Several short trails provide loop hikes through the tall Douglas fir, western red cedar, western hemlock, and grand fir trees. The west side of Lewis and Clark State Park emphasizes horseback use. Camp beneath the forest for $17 (no hookups or reservations) April–September.