There is established the Lewis and Clark Highway, which shall be composed of the following existing routes: State route 193 from the junction of state route 12 at Clarkston to Wawawai River Road; state route 12 from Clarkston to Waitsburg; state route 124 from Waitsburg to Pasco (west); state route 12 from Pasco to Waitsburg via Wallula and Walla Walla (east); state routes 395 and 82 from state route 12, through the Tri-Cities region, to the junction at state route 14; state route 14 from the junction of state routes 395 and 82 to Maryhill; state routes 14 and 5 from Maryhill to state route 432 through Longview to state route 4; state route 4 from Longview to the junction with state route 101 near the vicinity of Johnson's landing; state route 401 from Naselle junction to Megler; state route 101 from Megler through Ilwaco and Seaview to the junction with state route 4; state route spur/alternate state route 101; state route loop 100; state route spur 100; and state route 103.