I had never left the country until my honeymoon (when I was 22, almost 23).
I, too, have a reason for that. My parents loved to travel - in fact, there are only about a dozen states I haven't been to. But my father has some kind of inner ear thing that prevents him from flying, so everywhere we went, we drove. The summer b/w my freshman & sophomore year in high school, my parents went to Canada, but I chose not to go so I could 1-take driver's ed (it was hard to enroll in during the regular school year), and 2-hang out w/ my friends. My parents never had the desire to go to Mexico. If it wasn't reachable by automobile, we didn't go.
In high school I dated a guy who had never been out of the state of Florida!