The intent of this dissertation is three-fold: 1) identify transportation related barriers impacting visitation to national parks by racial/ethnic groups, and the effects of transportation on the visiting national parks, 2) identify the differences in indicators of the transportation recreation opportunity spectrum among racial/ethnic visitors and across recreation settings, 3) measure spatial accessibility of national parks and the effects of spatial accessibility and other factors on visitation to national parks among racial/ethnic groups. The first phase of research is designed to identify barriers to visiting national parks that are related to marginality, subculture, and discrimination hypotheses, and examine the effects of transportation incentives on visitation among racial/ethnic groups. Study results found that racial/ethnic minority groups visited national parks less frequently than Whites. Hispanics were more likely to perceive transportation-related barriers to visiting national parks than Whites. Moreover, providing transportation incentives can increase visitation by Hispanics significantly. The second phase of research developed indicators for a transportation recreation opportunity spectrum (T-ROS), and examined the differences in desirability for T-ROS indicators among alternative transportation modes, different types of recreation settings, and different racial/ethnic groups. Study results identified the important indicators for transportation service in different types of recreation areas, which can help inform transportation planning and management for the NPS. The final phase of research examined the spatial accessibility of national parks from different geographic locations by incorporating geospatial analytics, assessed the spatial accessibility of different types of national parks among racial/ethnic groups, and estimated the effects of spatial accessibility on visitation to national parks. Results showed that Hispanics and Blacks had higher accessibility to national parks than Whites within short distance radii, however, Blacks and Hispanics were more likely to perceive distance as a barrier to visiting national parks than Whites. Study results can help the NPS understand the spatial structure of national parks, provide visual information for visitors about proximate national parks and recreation opportunities, and identified effective management strategies for enhancing visitation of racial/ethnic minority groups from different geographic areas.