I just did this a couple of weeks ago using a non-profit organization, made up of active and retired phone company personnel. This groups is called the VerizonPioneers. One of their "things" is painting the US map, and also the solar system, on school playgrounds.

It was great. Once we had the new asphalt put in we set this up. She came down on a Sunday and we had about 15 volunteers.

She had a plastic sheet with 2" diameter holes. Once in position we went around and spray painted the dots. We then used rollers and the supplied paint to connect the dots. Then we went about following a special grid card to color in the states. Lastly water was painted around the coasts.

The group even supplies a games booklet that can be used by the staff to help with instruction.

Google them, VerizonPioneers, and select the local group. Contact them and see what they can do.

Good luck,
PresidentJim