Although not as strict as Canada's sounds, I think most US cities take a very dim view of substantial past drug use. For example, the following is from the list of "Automatic Disqualifiers" for my city's PD recruitment
Link (pdf):
[ QUOTE ]
- Illegally sold, produced, cultivated, or transported marijuana for sale.
- Illegally used marijuana for any purpose within the past three years.
- Illegally used marijuana, dangerous drugs or narcotics other than for experimentation. The use of an
illegal drug is presumed to be not for experimentation if:
1. The use of marijuana exceeds a total of 20 times or exceeds 5 times since the age of 21 years.
2. The use of dangerous drugs or narcotics, other than marijuana, exceeds a total of 5 times, or
exceeds 1 time since the age of 21 years.
- Illegally used marijuana while employed or appointed as a peace officer.
- Illegally sold, produced, cultivated, or transported for sale any dangerous drugs or narcotics, other than
marijuana.
- Illegally used dangerous drugs or narcotics, other than marijuana, for any purpose within the past
seven years.
1. This includes, but is not limited to:
a. Cocaine/crack, heroin, opium, morphine, LSD/acid, methamphetamine/speed, peyote (except
during religious ceremonies), mescaline, or derivatives thereof or steroids after 1994.
- Illegally used dangerous drugs or narcotics while employed or appointed as a peace officer.
- Had a pattern of abusing prescription medication.
[/ QUOTE ]
Not sure how much different it would be in smaller towns, etc. If anything, it might be even more of a "zero-tolerance" thing.