STRETCHING ACROSS the northeast corner of the state, from Tonasket to Newport, State Route 20 crisscrosses Washington’s final frontier. Here, deer outnumber people, and grizzlies, wolves, and caribou still roam the hills. Loggers, ranchers, and miners continue to work this land as their ancestors did more than 100 years ago.

From Tonasket along the Okanogan River, SR 20 heads east, twisting and climbing into the pine-scented Okanogan Highlands. You can camp and fish at the serene Five Lake Recreation Area (fs.usda.gov/okawen), take an easy hike among 600-year-old larches in the Big Tree Botanical Area, or go on an allday heart strengthener up 7,257-foot Mount Bonaparte.

Stop in Wauconda, which once boasted 300 residents. Just two live here now, and they own the entire town—a service station, café, and post office. Continue east to the charming little gold-mining city of Republic. You can prospect for fossils at the Stonerose Interpretive Center and Eocene Fossil Site, where hammers and chisels may be rented, or be a dude at the K Diamond K Guest Ranch (kdiamondk.com).

Now the Sherman Pass Scenic Byway, SR 20 winds through the Colville National Forest (fs.usda.gov/colville) to 5,575-foot Sherman Pass, the highest highway pass in the state. Here along the lofty Kettle River Range, hike, mountain bike, horseback ride, or backcountry ski on more than 40 miles of ridge-hugging trail. Stop at the White Mountain Fire Interpretive Site and CCC Camp Growden, or stroll along the Log Flume Interpretive Trail, lovely in autumn when larches and cottonwoods paint the hills gold.

In Kettle Falls, visit St. Paul’s Mission, an 1847 chapel built by Jesuit missionaries and Native peoples at the confluence of the Kettle and Columbia Rivers. Lake Roosevelt, formed by the Grand Coulee Dam, is just downriver and is administered by the National Park Service. Enjoy boating, water-skiing, fishing, camping, and houseboating on this 150-mile-long lake.

In Colville, relive the past in this former Hudson’s Bay Company outpost at the Keller Heritage Center Museum (stevenscountyhistoricalsociety.org) with its old sawmill and fire tower among its 5,000 artifacts. Then it’s off to the Little Pend Oreille National Wildlife Refuge (fws.gov/littlependoreille/) along the Little Pend Oreille River, where excellent birdwatching, hiking, hunting, fishing, cross-country skiing, and snowmobiling can be enjoyed.

Stop at the historic Tiger store, one of the last remaining buildings in this once thriving community, before heading south along the beautiful Pend Oreille River. Cross the river at Usk to see the Manresa Grotto, a sacred cave on the Kalispel Indian Reservation (kalispeltribe.com). Complete your trip in Newport straddling the Idaho border. An evening at Bead or Diamond Lake serenaded by loons makes a great way to complete your day. —CRAIG ROMANO