In this day and age Bed bugs can come from just about anywhere. Most often public places are where they a known to infest humans. Places such as libraries, school, hospitals, etc.
You could also be getting them from neighbors. In this event you would most likely be living in some sort of apparent or town house where the neighbor’s wall is attached to yours. Bed bug will travel though the wall and into your dwelling.
Often times bed bugs will travel on anything material such as, clothes and furniture. This makes getting second hand items very risky now-a-days.
Those are two main ways one would get bed bugs. For more information check out the rest of the website.