How to convince my parents to let me visit my boyfriend?

i'm an 18 (almost 19) year old female. i met my boyfriend in college and he lives about 6 hours away from me. i want to take a greyhound to go visit him but my parents aren't okay with that idea. i feel that i should be able to make my own decisions being that i'm an "adult" but i don't know how to handle the situation since i have always followed their orders all of my life. it's difficult for me to "break free" because my parents are divorced and i live with my mom (who seems to worry extensively about everybody being a bad person i.e. rapist, murderer, robber, etc.) i just want to live my life, make my own choices, and learn from MY own mistakes... does anybody have some advice that wouldn't be too pushy on them (since i still have to live with my mom and deal with my dad) and that they would be okay with?