In 1907 Cannan fired off a round at local rating of site values. It hit home. First he recited the logic of what today we call the “tragedy of the commons” (it was common coin long before Garrett Hardin). Then he pointed out that a city taxing only site values to provide free public services would attract too many people and too much capital. A city is an “open economy,” free to immigration of everything but land, something like an open range or fishery. Even if all cities tax only site values, cities with more rents per head may support public services at higher levels, and so attract immigrants. This distorts locational decisions, attracting people to jobs of lesser productivity where they may gain from better public services. This is “Cannan’s Law.”
In Andelson, Robert (ed), Critics of Henry George, rev. ed., 2003)