A bit of Washington State trivia: What was the first ferry route run by Washington State?
The Keller Ferry route across the Columbia River was taken over by the State in 1930 (wsdot.wa.gov/ferries-keller-ferry) and is still opperated by the State of Washington. The ferry connects Highway 21 across the Columbia (now Lake Roosevelt) at the junction with the Sanpoil River.
Ferry landing on the north side
A ferry has operated at or very near this site since at least 1890 (https://www.historylink.org/File/11072). In the early days the crossing was classic cable system that used the powerful flow of the river to drive the boat attached to a cable across the river.
Keller Ferry prior to Grand Coulee Dam
The dock on the south side
Looking north across Lake Roosevelt
The ferry is free. As noted in the History Link, the ferry began operation as a free ferry in 1930 due to a restriction on federal funds for the overall improvement of the highway. The ferry also runs 'on demand'. If you pull up to the landing the boat captain will proceed over to pick you up.
Highway 21 is not a heavy traffic route, particularly in winter like the day of my crossing. Further, the road up from the Columbia River to the high plains to the south is a steep 1,100 foot climb with hairpin turns. However, this route in the late 1800s and early 1900s was good way to get into the mining districts of the Okanogan Highlands and was also a route to move sheep mostly from the drier plains to the south across the river to the moist high summer meadows in the mountains of the Okanogan Highlands.