We used the TravelTime API to calculate the area that can be reached by car in 1 hour from the city center in both peak and off-peak hours. We collected this data for the most populous city in every state in the US, the 20 most populous cities in the UK, all European capitals and the world's biggest metropolitan areas covered by TravelTime.

Registered vehicles data was sourced from WHO and populations were sourced from WorldOmeter.

The data was collected in November 2020.