I heard someone on the radio say she was riding on the transcontinental bike trail. I had never heard of one. An internet search came up blank. Is there one?

Maybe they were referring to the TransAmerica Trail? Or possibly it was "Transcendental" rather than Transcontinental (as in the Great Divide route)?

Many ways to travel, to ride your bike from the Atlantic To the Pacific US Seashores

Adventure Cycling Route Network | Adventure Cycling Association

Possibly TransAmerica Trail | Adventure Cycling Route Network | Adventure Cycling Association

Probably referring to the original Bike Centennial route (now Adventure Cycling) from Virginia to the mouth of the Columbia River in Oregon.

Wouldn't it be wonderful if there were a dedicated bike road that crossed the country. Or a whole system of dedicated bike roads.

East-West Across US created by Adventure Cycling:

Trans-America

The Norther Tier

The Southern Tier

North-South US:

Great Divide

Mississippi River Trail

East Coast Greenway

Pacific Coast

I would love to ride one of these routes one day.

ACA's Trans Am is named a "trail." Over the years, several people on this and ACA's forum have interpreted that to mean the route is an off-road route. While some of the route utilizes trails (e.g., between Lolo and Hamilton, MT), the overwhelming majority of it is on paved roads.

What do you mean? Dedicated exclusively for bikes? If so, don't hold your breath. However, ACA is involved with creating the U.S. Bike Route System:

U.S. Bicycle Route System (USBRS) | Adventure Cycling Association

Soon they will start working on the Chicago to NYC portion in earnest.

Every time I read or hear something like that, I think about the bike path between Fairplay and Alma, CO. No doubt it was built at great expense. But since only bicyclists ride on it, maintenance just didn't happen. As a result it was one of the roughest, most dangerous part of the TransAm. I'd rather share a road with a few hundred vehicles an hour than ride that. (And I did get on the road!)

You mean the Transcontinental trail that runs from Mexico to Canada on the spine of the rockies? Bikepacking route, some singletrack, mostly dirt roads with some paved. Check out the great divide trail.

Even the Great Divide Mountain Bike Route is not completely car-free. Some portions are actually on paved roads, and some (perhaps many) of the unpaved roads are open to vehicles. Indeed, several years ago a participant in the GDMBR race was struck and killed by a pickup truck on an unpaved portion of the route.

This is a great idea, but also pretty funny given your username.

Turns out there is an east-west off road trail for motorcycles/4x4, Its not all dirt, but the vast majority is non-paved. A couple from Ohio is trying to ride it, below is the link to their story and background info on the trail.

SBW x TAT

Cool, I did not know that route existed. And it even has one end in Oregon. I wonder if the many dual-sport motorcyclists I know know of it.

Thanks for the link.