Google is using the pre-registration numbers of each area to help to determine where they'll be expanding. If you want an alternative to Comcast/Cox/Fios , check out the links below and add your address:
General Info:
https://fiber.google.com/plans/residential/
Pre-register your address:
https://fiber.google.com/cities/
This has been crossposted in the NoVA/SoMD forums as well since we all sort of function as one area.