Most people don’t know it, but there is an official U.S. Bicycle Route System (USBRS), albeit fledgling. The first two routes were established in 1982, primarily through Kentucky, Virginia, and North Carolina.
For the next 20 years, there wasn’t much interest by anyone with power (or money) in expanding the USBRS. Beginning in 2003, AASHTO and the Adventure Cycling Association began began making progress, which finally resulted in a 2008 map showing potential corridors to be added to the USBRS. It’s important to note that the map didn’t identify actual routes, just search corridors, defined as a 50-mile-wide area, with the actual routed to be determined at a later date by individual states.
Since then, only a handful of states have formally applied to have routes formally recognized in the USBRS, with the first new routes added in May of 2011 (Maine, New Hampshire, Michigan, and Alaska).
If a nation-wide bicycle route system is a national priority, there should be a federal funding source attached, including oversight and guidelines from the Federal DOT. Without the promise of federal financial assistance, there’s really no incentive for states to participate, and very little promise that investment in the USBRS will bring more economic benefit (in the form of tourism) than simply investing in a system of State (or regional) bicycle routes.
At the same time, the routes identified by AASHTO for inclusion in the USBRS undoubtedly mirror routes that would have been (or already have been) developed or designated as State (or regional) bicycle routes, so there’s also very little reason for states not to participate in the creation of the USBRS.