BackgroundHigher traffic speeds increase the risk of serious or fatal injury to child pedestrians and may deter parents from encouraging their children to walk to school. This cross-sectional study examined the association between measured vehicle speed and active school transportation. MethodsThe study sample included public elementary schools in Calgary (n = 46) and Toronto (n = 42), Canada. Speed limits in school zones were 30 km/h in Calgary but ranged from 30 to 60 km/h in Toronto. In May and June 2018, trained observers counted children arriving to school and recorded their mode of travel. Vehicle speeds around schools were measured between 07:30 and 18:00 (school activity hours) and quantified as the 85th percentile speed, the percentage of vehicles exceeding 30 km/h, and the percentage of vehicles exceeding the speed limit. Multivariable beta regression was used to examine the relationship between vehicle speed and active transportation to school for each city, adjusting for school environment features. ResultsA high percentage of vehicles were travelling over the speed limit in front of schools: 45% in Calgary and 42% in Toronto. No association between vehicle speed and active school transportation was found in Calgary (mean 85th percentile speed OR: 0.99, 95% CI: 0.93, 1.06). There was an inverse association between vehicle speed and active school transportation in Toronto, where for every 1 km/h increase in the mean 85th percentile speed, the odds of active school transportation decreased by 3% (OR: 0.97, 95% CI: 0.95, 0.99). ConclusionThere was a high prevalence of speeding in front of schools, which could increase the risk of traffic-related injuries and fatalities to children. Speed limit reductions to 30 km/h on roads near schools may be a useful preventive intervention in Toronto during school activity hours. Such targeted interventions can help improve child pedestrian safety and promote active school transportation.