This data is from national censuses of France. Paris arrondissements were redefined in 1860, when the city annexed considerable new territory. Central city population loss was already evident. Central area population losses started much earlier. Before the present boundaries of Paris were established in 1860, the former inner 4th and 9th arrondissements lost population starting in the 1817-1831 census period. The 7th arrondissement had a population density of 233,035 per square mile in 1856, down from 258,820 in 1846 (89,905 and 99,853 per square kilometer respectively). The 1846 figure was the highest density ever recorded in a Paris arrondissement. Inside the former boundaries of the city, the population density reached 88,539 per square mile in 1856 (35,684 per square kilometer). The former three inner arrondissements (4e, 7e and 9e) reached their population peak in 1836.