The catch being "federal involvement." Any federal money spent, even pass through money in the form of grants administered by states or local entities, triggers a Section 106 review to determine if the proposed federally funded action endangers or alters the National Historic Landmark status. This is usually determined by the SHPO, and it is about the only way local interests can be heard. This is a delaying tactic, as after 6 months, the proposed action can continue anyway. We used it to get a better post office design for Silverton when a double-wide trailer was proposed. The 106 reviews don't automatically happen, so usually someone affected by the action has to be on their toes and call this review into action. And often the SHPO will contact someone locally to find out what the proposed action is all about, so it is important to know your state SHPO and let them know that there are interested people or groups in a community who care about historic preservation. In our case, it is our local historical society.