I thought I'd do a Google Maps search.
Yonge Street ends in a T-intersection and the last address on that street is only 20461 Yonge Street.
Only 20461... HIGHER :D
Printable View
87,342 :)
301-501 :idea:
301502 :)
301503 :dozey:
13? :d
403257?
Higher than 403257.
Rollo - something just came to me in a fit of enlightenment. Does your question mean the highest actual street number i.e. the commonwealth style of numbering starts at 1 and counts until there is no more land left on said street. Or does it include the U.S. urban system that includes the block number before the building number eg 34512 South 5th Street would mean block 345 to the South of the dividing line on 5th street, letter box number 12