In North America the housebuilding industry is ubiquitous and locally autonomous. In Ontario during the 1990s, 81% of urban single‐family homes were erected by locally based builders, a proportion that varied with urban isolation. Urban areas may be regarded as the industrial districts of home builders: numerous small, specialized firms interact frequently within a rich, embedded market network; subcontracting is the norm; networks and firm boundaries are fluid. The theory of industrial districts offers a useful vocabulary for analysing the neglected building industry. Analytically, the building industry offers unequalled opportunities to explore the dynamics of industrial districts, and how economic globalization meets local limits.