1870 Birth:1793 Birth in January 1870 based on age (6 months) in 1870 census enumeration; birth place of Chicago Ward 6, Cook County, Illinois assumed based on his parents enumeration in that location.

1870 U.S. Census:1793 William enumerated in the household of his parents Andrew and Alice Ryder in Chicago Ward 6, Cook County, Illinois as a male, age 6 months, white, at home, born in Illinois, born in January 1870. The family is clearly enumerated as Reilly, not Ryder.

1880 U.S. Census:418 William enumerated in the household of his parents Andrew and Alice Rider in Chicago, Cook County, Illinois, as Wm. C., white, male, age 10, son, at school 6 mos. this year, born in Illinois, father born in New York, mother born in New York.

1892 Marriage:932,1953 Estimate marriage year of 1892 based on length of marriage (8 years) given in 1900 census enumeration and birth of son Andrew in January 1893, as stated on Andrew's 1959 death certificate.

1900 U.S. Census:932 William enumerated in the household of his mother Alice Ryder in City of Chicago, Town of the Lake, Cook County, Illinois, as son, white, male, born Jan. 1870, age 30, married 8 years, born in Illinois, father born in New York, mother born in Illinois, skalpro [scalper?], employed all year. William's son Andrew T. and grandmother Helen A. Burton also residing in household.

Death Before 1921:740 William not mentioned as a surviving child in father Andrew Ryder’s death mention.