A first step in explaining the processes which result in a redistribution of population over time is the identification of patterns and trends. A very useful tool to this end is centrographic analysis. The centrographic measures, centre of gravity, standard distance and a measure of relative dispersion, are determined for the population distribution of Québec at varying scales (county, region, province) for three points in time (1951, 1961, 1971). At the first level, the large majority of the counties either exhibited stable patterns or tended toward concentration. At the regional level, population tended to concentrate in all but two of the administrative regions studied — Abitibi and Gaspésie. At the provincial level, there has been a general trend toward concentration. The centre of gravity of the population, while remaining in the environs of the municipality of Nicolet, is wending its way progressively toward Montréal.