In this study, we use estimated public transit routes for high school students in Baltimore City to predict the number of days they are late during the school year. We find that after adjusting for individual and school characteristics, school preferences, and neighborhood fixed effects, total travel time and transit use are not predictive of tardiness, but requiring a bus transfer is. These estimates do not vary by student or school characteristics, indicating that this is a general phenomenon that has more to do with system-level reliability than individual motivation or school climate. These findings highlight the hidden costs imposed on some students who wish to leave their neighborhood and travel across town for better educational opportunities.