The State Primary Road System
is an administrative system used to track roads within
the state that are maintained by the Kentucky Transportation
Cabinet. Roads, streets and/or highways are classified
by the type of service and function the facility provides,
as follows:
State Primary Routes:
Interstates (symbolized by black lines on the maps), parkways
(symbolized by brown lines on the maps) and other long-distance,
high-volume intrastate routes (symbolized by red lines
on the maps) that are of statewide significance. These
routes generally link major urban areas with the state.
State Secondary Routes:
Shorter distance routes of regional significance with
both access to land use activity and mobility as their
functions. These routes generally serve smaller cities
and county seats within a region. Symbolized by green
lines on the maps.
Rural Secondary Routes:
Routes of subregional significance with access to land
use activity (such as farm-to-market routes) as their
prime function or urban arterial streets or other collectors.
Symbolized by yellow lines on the maps.
Supplemental Roads:
Routes that are state-maintained for various reasons but
are not included in the higher classifications. They are
generally short-distance routes such as frontage roads,
cross roads or local access roads. Symbolized by purple
lines on the maps.
See also our State
Primary Road System maps. 
