when you look at a sectional, and see a VR route, if it has 4 digits, least one segment is going to be below 1500' AGL, if it has 3 digits VR XXX, all of it is going to be above 1500' AGL.
VR routes are aerial corridors across the United States in which military aircraft can operate below 10,000 feet faster than the maximum safe speed of 250 knots that all other aircraft are restricted to while operating below 10,000 feet. The routes are the result of a joint venture between the Federal Aviation Administration and the Department of Defense to provide for high-speed, low-altitude military activities.