17-229-207 Me. Code R. § 2
Each municipality may adopt its own Adopt-A-Highway Program for litter control and beautification activities. Should a municipality want to erect signs on or adjacent to state highways and town ways the following rule shall apply.
The Department may allow a municipality which wants to establish an Adopt-A-Highway Program for litter control and beautification activities, a permit for up to four sign assemblies. Each sign assembly may not exceed 50 square feet. Each component panel identifying the individual, business organization or nonprofit community organization participating in litter control or beautification activities shall not exceed four square feet. Upon approval by the Department, each sign assembly and attached panels will be installed and maintained by the municipality.
Application for a permit to erect an Adopt-a-Highway sign assembly shall be made on forms furnished by the Department. The Department shall have final responsibility and authority to determine the specific size and location of any sign assembly. Sign assemblies not deemed to meet the intent and purpose of the law or the criteria established in this rule shall not be approved or erected.
Sign assemblies shall not be permitted at locations within the highway right of way which adversely impact the use or safety of the highway. Sign assemblies may be erected outside the highway right of way on publicly owned property. Sign assemblies shall be located so as to avoid visual conflict with other signs, have the least impact on scenic and background environment, and take advantage of the natural terrain.
No sign assembly nor litter control and beautification activities shall be permitted within the right of way of any state highway which is an interstate highway or a fully controlled access highway.
17-229 C.M.R. ch. 207, § 2