Although it says "USGS Store" you can view almost any map that the USGS has published in the past 100 years.
The drawback is that these files (scanned maps) are huge and might be problematic downloading on the road.
Also, they might be tough to read on a smartphone - less so on a note pad.
Some of the 1:250 and 15 minute maps are terribly outdated. Even the 1:100 are often old, now.
Most 7 1/2 minute maps have been updated, but the level of detail may be more than you need.
ACA maps are great if you don't plan to wander off route - but of little use if you do.
I have found that National Forest maps are ideal for cycling - the scale is 1inch = 2 miles.
Many have topo contours now and most are now available in plastic.
Crossing the Cascades might entail two or three maps - same for the Rockies.
They have campground, backroad, trail and facilities information.
Plus, land ownership status for those who wish to do dispersed camping.