Background. Lack of spatial access to care has been associated with later stage at diagnosis and poorer outcomes in multiple cancer sites. However, these relationships often do not hold in urban areas. Most analyses measure spatial access to health care using driving as the assumed mode of transportation. This assumption may not be appropriate among people living in urban areas with access to public transit, or among populations burdened by cancer disparities. The purpose of this research is to develop a measure of travel burden appropriate for measurement of public transit trips to care and evaluate its relationship to colorectal cancer survival in Chicago residents. Methods. Using publicly available data about the Chicago public transit system, a GIS network model was built and used to estimate the time, number of transfers, and cost of a trip. Addresses of incident colorectal cancer cases residing and treated in Chicago from 2006 to 2008 and their diagnosing facility were obtained from the Illinois State Cancer Registry and geocoded. Survival time from diagnosis was ascertained through linking to the National Death Index. For each case, a public transit trip to the diagnosing facility was modeled and a comparison driving trip was estimated using a web map incorporating traffic data. A travel burden score was calculated as the sum of standardized components for each case and travel mode. Travel burden score was used to predict survival among Chicagoans diagnosed with colorectal cancer, adjusted by demographic and neighborhood covariates. Results. Travel burden via both driving and public transit was associated with race/ethnicity, neighborhood concentrated disadvantage, neighborhood primary care, and age at diagnosis of cases. Transit burden score was significantly associated with colorectal cancer survival (HR: 0.87, 95% CI: 0.80, 0.94), while driving burden was not (HR: 0.94, 95% CI: 0.88, 1.01). Inclusion of travel burden in models did not alter the effect of race or ethnicity. Conclusions. Burden of public transit trips to care is significantly associated with survival among Chicagoans diagnosed with colorectal cancer. However, this effect is protective and does not account for racial or ethnic survival disparities. This result may reflect patient decisions to seek out higher quality facilities regardless of convenience. It may also arise from the geography of Chicago in which several neighborhoods with high disadvantage and cancer burden are also located near high volume hospitals.