Maryland was a state.
Alpha along with her daughter and husband may have been from Maryland or a surrounding Mid-Atlantic state. As they took shelter in Baltimore in the early days of the outbreak where they met other survivors including Amanda, Cyrus, Lamar, Rose, and Matias. This soon went awry when Alpha smothered Mathias to death causing him to turn into a walker. This was due to the fact that they weren't aware of everyone turning when they die.
The Garcias lived in Baltimore prior to the outbreak.
Many road maps take place in Maryland and many characters are from here.