The Code of Virginia requires that goals relating to jobs-to-housing ratios be considered when projects are selected for the state's transportation program. Because the code does not specify the relative importance of the jobs-housing balance, this paper examines its influence on average jurisdiction commuting times. After regional differences were controlled for, the correlations between shorter commuting times and higher jobs-labor force ratios were from -.71 to -.76 for 1980, 1990, 2000, and 2006 data sets. A 20% increase in the 2000 ratio led to travel times being decreased by 5.3 min (about 18.5% of the statewide average). However, higher ratios may be associated with better transit service or other variables. Correlations alone do not prove causality and are potentially misleading. Consequently, a longitudinal model was developed that predicted changes in commuting time from 1990 to 2000 for each urban Virginia jurisdiction examined. This model estimated that the average impact of a given urban jurisdiction improving its balance by 20% was a reduction in commuting time of 2.2 min (7% of the average urban value). This effect is evident only if several factors, such as the manner in which the region is defined, are carefully controlled for. Otherwise, commuting time is not significantly affected by a change in balance. This finding suggests that the jobs-housing balance has a statistically significant impact on commute-related travel, but that the impact is more modest than a correlation-only analysis would suggest. Modifications necessary to apply this approach at a census tract level of analysis are discussed.
