Abstract: For at least two decades, urban policy in Australia has been based on the belief that high levels of car use and poor public transport are mainly the result of low urban densities. There has been considerable debate about the evidence on which these policies are based, but until recently there has been no common data-set that allows densities and transport patterns to be compared on a consistent and rigorous basis. As a result of recent changes to data collection and publication systems by the Australian, Canadian and United States national census agencies, it is now possible to compare urban densities and transport mode shares (for the journey to work) across the three countries’ urban areas on a consistent basis. This paper presents the results of this comparison. Australian cities have similar densities to those of Canadian cities and the more densely-populated US cities. There are variations in density among cities, but these show little or no relationship to transport modes share, which seems more closely related to different transport policies. These findings are very different from those on which current urban policies are based, and suggest the need for a radical rethinking of those policies.