Most drug possession charges these days are being dismissed or withdrawn, however once you have been fingerprinted, the criminal charge can be seen in a background check.
If the Americans see that you have been in trouble with drugs, even if the charges were withdrawn, dismissed, stayed, absolute or conditional discharge then they can still turn you away at the US border.
Once a file destruction is completed to remove your prints, photos, court and police records you will be safe to travel.
A US Entry Waiver is only needed if you’ve been denied entry to the US.
Here is a recent thank you letter we received from a person we helped in Winnipeg who had a charge of marijuanna posession, that was later dismissed: