Q15 - Indicates if arc is also a boundary for a 15 minute quad. 0 - arc is not a 15 min. 0 - arc is not a 7.5 min. Each quad is annotated with the quad name. This data set was created to serve as base map information.
Data are appropriate for use at a regional scale and are intended as a reference.
Data are not appropriate as a geodetic or engineering base. New tics were generated as well, one at each quad corner. Latitude and longitude values were assigned to the arcs in the generation process. The data were projected to Lambert Conformal Conic. Arcs forming quadrangle boundaries for any 1 x 2 degree quadrangles intersecting Illinois were extracted to this data set.