A GIS database derived from sub-meter GPS data was developed for the Going-to-the-Sun Road (GTSR) in Glacier National Park during 2000 and 2001. The GTSR is a National Landmark status road that offers visitors to Glacier the opportunity to transect the park and all of its varied habitats. The GTSR is in need of long-term rehabilitation to repair years of damage due to extreme climatic influence, such as avalanche and rockfall. Developing a high resolution GIS database of the road and its associated infrastructure has provided a consistent map base for engineering and cultural/historic inventory and design studies that are part of the long-term rehabilitation plans. The road centerline was initially mapped, from which a milepost data theme was derived. The park's DOQQ data (1:12000 scale) were used to verify this and subsequent GPS data collected. The milepost theme provides the common spatial context, or map base, for engineering and cultural resource inventory efforts. Other themes mapped include pullouts, retaining walls, guard walls (historic fabric), drainage structures (culverts, etc.), Federal Highway Administration (FHA) survey points, wayside exhibits, avalanche chutes, and intersecting roads and trailheads. Linkages were established with GIS data to relational databases describing retaining wall condition (FHA) and assessment of historic guard wall condition. The GTSR GIS database is maintained to reflect changing road conditions and is widely distributed to contractors associated with road rehabilitation efforts.