Geographical information systems for mapping maternal ground transport to level III care neonatal centers. 
The objective of this investigation was to determine maternal ground transport times from community hospitals to the nearest hospital offering comprehensive (level III) neonatal care within the contiguous United States.  This observational study combined data from the 2010 U.S. Census tract and 2010 American Hospital Association Annual Survey.  Level III (full complement of care) neonatal centers were plotted using 2010 geographical information systems (GIS) mapping software (ESRI, Redland, California, United States).  Locations of level I (uncomplicated care) and level II (limited complicated care) centers and residences of reproductive-aged women (18 to 39 years old) were mapped to identify maternal ground transport times to level III centers.  Most of the 584 level III neonatal centers were located in metropolitan areas (83.5%).  The proportions of level I and level II hospitals within a 30-minute drive of a level III neonatal center were 19.8 and 47.3%, and 52.2 and 69.8% were within a 60-minute drive time.  Ground transport times were shortest in the Northeast and metropolitan areas, and longest in the rural Great Plains and noncoastal West.  GIS mapping enables health providers and health policy makers to better understand maternal ground transport times to current and future regional hospitals offering level III neonatal services.