Can data from the decennial census measure trends in mobility limitation among the aged?

We evaluate whether trends in the prevalence of disability among the aged can be investigated using the 1980 U.S. Census' public transportation question and the 1990 query on mobility limitation. Despite the obvious difference in the two questions, we found remarkable similarity in major cross-sectional patterns, such as those by age and sex, when comparing results from the two data sets. This result, coupled with the large number of observations available in the U.S. censuses, suggests that census data may be a suitable data source to study mobility limitation patterns in the small subgroups of the population that are frequently underrepresented in sample surveys.