I'm an American living in Canada.
11 years ago, when I was 19, I was stupid and had some pot in my car while driving through a border patrol checkpoint. (Note: A border patrol checkpoint is not the same as a border crossing. A border patrol checkpoint is well-within the US; it is run by border patrol agents, not customs agents.) Long story short, the police dogs found the pot and I was issued a misdemeanor ticket for possession, which required a fee of $300.
Since then, every time I enter the US from abroad (which happens several times a year), the US customs agents give me a hassle about my "drugs at the border event", as they put it, and invariably pull me and my family aside and search through all my things. It's not only embarrassing, but it adds anywhere from 20 minutes to 2 hours to my travel time, which makes catching planes tough.
Is there any way I can clean my record of this offense, so that I don't get pulled over every time I enter the US?
EDIT: Clarification: I was not arrested. At the time of the incident, the border patrol agent issued me two tickets (on a standard "traffic citation" form): one for "possession of marijuana" and one for "possession of paraphanalia". After he wrote up the tickets, he let me drive away. The tickets said I was to appear in magistrate court some time later. Instead, I opted to send via snail mail a check and a letter stating that I plead no contest to the tickets. (In hindsight, this may have not been the best move. Did I mention I was young and stupid?)