This study examines trends in the mobility of older adults in the USA between the years 2001 and 2017 and how mobility varies among 5-year subgroups of older adults from 55 to 80+ years. Based on data from the 2001 and 2017 National Household Travel Surveys (NHTS), we use descriptive, graphical, and multilevel regression analysis to detect differences in travel behavior and its determinants. Mobility tends to decrease with age, even after controlling for density, gender, race, income, employment, medical condition, car ownership, and having a driver's license. Compared to younger age groups, older adults were more likely not to make a trip during the travel day. Among mobile individuals, older adults made more trips but traveled fewer miles per day. Mobility declined for each of the successively older 5-year age categories. The 80+ age group had, by far, the lowest levels of mobility. Older age groups increased their mobility relative to younger age groups between 2001 and 2017.