A few years ago, I decided to combine my love of baseball with my love of travel and try to see my favorite team, the Washington Nationals, in all the ballparks I had yet to visit. And last year, I finally coaxed my baseball-tolerating girlfriend to come along with me. There are 30 major league teams in 26 cities, 18 states and 2 countries. Turns out baseball tourism is a really good way to see the country.