A puzzling phenomenon that I should have recalled when this thread started relates to the "pilots' name" for Seattle, WA.

Due to lots of recent buildup of residential areas in what should be unspoiled areas, lots of "neighborhood associations" have formed, with restrictive rules prohibiting the parking/storage of boats, trailers, and other "recreational items" where they are "visible from the street."

It obviously is quite important to those who create and manage these little empires that the residents should not appear, visibly, to be enjoying themselves in any way, but should spend all their time mowing lawns and re-painting houses to conceal the shoddy materials and workmanship used in most of the newer construction.

Almost uniquely, in Seattle and immediately adjacent towns, it has been deemed that covering your boat/RV with a blue tarp makes it invisible (i.e. not visible from the street), and permits keeping it on your own premises.

As result, the air approaches into Seattle present a vision of thousands of tiny patches of blue tarp, resulting in the pilots' jargon of "Blue Tarp City" for Seattle.

I'm unaware of any decisions regarding the relative invisibility of things under other colors of tarp, but it is apparent that blue is the color (for sunfade properties) of the cheapest and most plentifully available ugliness (which is permissible) to avoid anyone being offended by the visible presence of anything "recreational."

John