OK, this is very bizarre. In 1900 George was an electrician: what I would consider a "growth" trade for the time. In 1910 he is in 4th ward, Manhattan (Series: T624 Roll: 1005 Page: 235) as a Coal Wagon Driver, age 35. Nellie is shown as 30 with 3 kids only 2 living: Mary 8 and Veronica 6. Implies William (b April 1900) from prior census died. They also had 5 boarders.
Can't find father William, so perhaps died or returned to Canada (latter unlikely, I think).
1920 still in Manhattan, and Nellie has died (Series: T625 Roll: 1207 Page: 207)
George 46 Widower, a chauffeur for Water Company
Veronica 15
Magdalene 9
Do not have access to 1930. Hope this helps.
Mods:
Possible (probable) death for Nellie: Jenkins Nellie 32 y Aug 25 1912 Cert # 24961 Manhattan
(from Italian Gen. Group database) Might also try their databases for other deaths and marriages.
AHA! George Jenkins married Sheehan, Ellen Jul 3 1899 in Manhattan Cert #12359
Nick