Purpose: Distance to provider might be an important barrier to timely diagnosis and treatment for cancer patients who qualify for Medicaid coverage. Whether driving time or driving distance is a better indicator of travel burden is also of interest. Methods: Driving distances and times from patient residence to primary care provider were calculated for 3,917 breast, colorectal (CRC) and lung cancer Medicaid patients in Washington State from 1997 to 2003 using MapQuest.com. We fitted regression models of stage at diagnosis and time-to-treatment (number of days between diagnosis and surgery) to test the hypothesis that travel burden is associated with timely diagnosis and treatment of cancer. Findings: Later stage at diagnosis for breast cancer Medicaid patients is associated with travel burden (OR = 1.488 per 100 driving miles, P = 0.037 and OR = 1.270 per driving hour, P = 0.016). Time-to-treatment after diagnosis of CRC is also associated with travel burden (14.57 days per 100 driving miles, P = 0.002 and 5.86 days per driving hour, P = 0.018). Conclusions: Although travel burden is associated with timely diagnosis and treatment for some types of cancer, we did not find evidence that driving time was, in general, better at predicting timeliness of cancer diagnosis and treatment than driving distance. More intensive efforts at early detection of breast cancer and early treatment of CRC for Medicaid patients who live in remote areas may be needed.