A few pointers on protecting trees from the billboard industry.

It is important to make this issue as  simple and understandable as possible.

There are no shades of gray here; this is simply an effort by the billboard industry to be allowed to destroy publicly owned trees for their private gain.  That's the issue in its entirety.  The billboard industry tries to obscure this by calling what they do "vegetation control."  However, the truth is that the "vegetation" is not out of "control"; what the industry is doing is cutting -- in some cases clear-cutting -- publicly owned trees for their own benefit.  Always refer to this practice as "tree-cutting" so that people know what is at stake.

The Federal Highway Administration does not endorse tree-cutting.

A 1990 memorandum of understanding from FHWA clearly states that they have rescinded their previous memo allowing tree-cutting and that states should end their tree-cutting agreements or programs.  Political pressure from the billboard industry has since caused FHWA to hedge on this issue and to say that, while they no longer endorse tree-cutting as a practice, right-of-way maintenance is a state concern.

A long string of court decisions makes clear that billboards have no "right to be seen."

The billboard industry wants the public to think that billboards have a "right to be seen" -- that is, that allowing trees to grow in front of billboards violates the rights of the billboard owners.  A long string of court decisions makes clear that there is no such right, including a North Carolina Court of Appeals decision, Adams Outdoor Advertising v. NC Department of Transportion, from September 21, 1993.

The destruction of publicly owned trees on the public right-of-way for the benefit of a narrow private interest has been found to be illegal. 

In Georgia, the Supreme Court ruled in 1995, that allowing the destruction of publicly owned trees on the public right-of-way for billboard visibility violated the state's constitution, because it constituted a gratuity to a private interest without providing a substantial benefit to the state or its citizens.

Allowing tree-cutting may in fact violate the law regarding the use of the public highway. 

The Code of Federal Regulations states: "All real property, including air space, within the right-of-way boundaries of a project shall be devoted exclusively to public highway purposes."  Clearly, allowing tree-cutting for no reason other than private (billboard industry) benefit is illegal.  While FHWA does not interpret the law this way, it could serve as a useful argument for you.