The official association map shows the highway crossing Donner Summit on both Donner Pass Road and Old Donner Summit Road, plus an alternative following US50 around the south side of Lake Tahoe.
Several years ago when traveling through that area in a car, I took Donner Pass Rd simply because it looked more interesting than I80.
It looks like, in most parts of the country, you can choose between I80 (or US30) or local roads, and not be far off. I see from the map that it used to follow Roosevelt Rd through the western suburbs of Chicago. I drove that plenty of times without any sense of driving something historic. Same would go for US20 through South Bend and Elkhard IN.