Is there a national equivalent to OS in the US? Or is detailed mapping more piecemeal according to each state?
Thanks.

no idea on the question but just watch your scale – remember dave gorman getting caught out ….state to a page and he would drive across a "page" and it took him like a day – then the next "page" would take 3 – they tend to change the scales to fit the page rather than spread the map out :d- could be quite a shock if you were out on your bike 😀

Yes, there is usgs topo mapping.

It is okay, but doesn't have rights of way markings, so you need more information to make it really useful. Also it is often 10-20 years out of date.

Free to downloadoff the web somewhere too, which is nice.

For trail/right of way information, use local tourist information, bike shops etc, and it is rare to need a map – they don't have the same complex trail networks we have over here. Maps are useful for back woods hiking, but most of those places bikes are banned.

Thanks Joemarshall – have just found the USGS shop online. I'm interested in plotting road rides rather than off-road so hope that they'll be detailed enough. Big place though…

I've done that with the scales while driving. Bit like Australia where you get a blank page with just a straight line across it and it's 1500km!