The first Directory of Toronto was published in 1833, when the total population was only some 9,000. In 1903 the forty-second issue of the City Directory of Toronto contained 97,087 individual names, exclusive of firms, corporations, etc. The estimated population for the city at the end of 1902 was 267,000.
By 1908 the directory has entries for 129,355 individuals, for an estimated population of 365,000. In a statistical table it shows 28,839 births and 20,051 deaths for the period 1903 to 1907. That's a net natural increase of 8,788. The remaining increase of some 90,000 was accounted for by people moving into the city, many of them part of the huge influx from Britain in the first decade of the 20th century.
Directories are a valuable resource for genealogy, and some Toronto directories for this period are now available at The Internet Archive. The links for these two years are: 1903 directory`and 1908 directory. Get to earlier Toronto directories, and other digital publication of the Toronto Public Library, here.