Redlining occurs where institutional mortgage lending is the norm and where lenders decline to loan in specific areas. The term originated during the 1930s in the United States, where it was promoted by federal agencies and acquired racial connotations. Recently, redlining has been uncommon in Canada, but contemporary reports, archival records and parliamentary debates show it was widespread from the 1930s to the 1950s. Contemporaries distinguished the ‘black‐balling’ of remote areas, where it was impossible to make loans, from the ‘marking’ of districts in urban areas where companies could lend but chose not to do so. Only the latter can be regarded as redlining. As defined by Canadian housing agencies, most ‘marked’ areas were in unregulated, owner‐built suburbs that lacked services. The suburban origin of redlining in Canada had little to do with the distribution of ethnic minorities. As long as it lasted, roughly until the late 1950s, it perpetuated social class diversity in Canadian suburbs.