The approach to the design and revision of electoral districts in Canada is quite different from that found in the United States, despite the two countries' sharing of the same basic first-past-the-post electoral system. As John Courtney notes in his careful study of the topic, in Canada the emphasis in defining electoral districts, or constituencies or ridings, has been underpinned by concepts such as “community of interest” and “effective representation,” which encompass a wide range of political and social considerations—many local in nature—and which permit substantial deviation from the principle of one person, one vote. At the federal level, the allowable deviation in the size of constituencies can be plus or minus 25% within any given province, with the possibility of even greater variances under special circumstances. At the level of provincial electoral systems, the variances can be even larger, in part due to the fact that in certain provinces the ratio of urban to rural seats is specified in law. At the same time, the actual process of designing and reconfiguring the boundaries of constituencies, in the hands of independent, arm's-length commissions for the past 40 years, has been remarkably free of direct partisan influence. In fact, given the rather tattered state of current Canadian parliamentary democracy, characterized by one-party dominance in the federal parliament and a precipitous decline in voter turnout over the past three elections, the institution of arms-length boundary commissions stands out as something that works well and enjoys broad respect.