Well before the onset of industrialization, Edo was one of the biggest cities in the world, with a population of one million or more by the beginning of the eighteenth century. For next 150 years, until just before Edo changed its name to Tokyo in 1868, it is believed that Edo maintained this population level of one million, with about a half of the population being samurai and their families. In 1872, having seen a massive exodus of ex-shogunal retainers and their families, triggered by the collapse of the Tokugawa shogunate and the social and political uncertainties that followed, Tokyo's population stood at just 580,000, close to half the previous size. In addition, it is believed, the city's administrative functions were rapidly deteriorating. The population began to recover from about 1880 and exceeded the one-million mark in the 1890s. In other words, as many as half a million people migrated to Tokyo during this twenty-year period. In 1908 when a population survey was taken, the total population was then 1,626,000, and the number of people, particularly males, in each of the age groups 15–19, 20–24 and 25–29 was greater than the number in the 5–9 or the 10–14 group. There is a marked contrast with the situation in the late 1860s when the 20–24 group was smaller than the 10–14 or the 15–19 group. This survey suggests that many of the migrants who arrived at Tokyo in the period of growth were male, young and, probably, unmarried.