Libertarian purists argue that government should have almost no power. Libertarian pragmatists argue that government power should be devolved to the lowest practical level. The pragmatists case is the better one, given that the urge to regulate social and economic practices is especially strong where people (and votes) are concentrated. Consider the following graphics:
Shades of purple indicate the spectrum of election preferences within counties. The deeper the shade of purple the higher the proportion of votes cast for Kerry.
Counties shaded pink, red, and purple have the highest population density.
Comes as no surprise does it? Nor does it matter if the urban-rural split reflects a difference in "values" or traditions. A fact is a fact. City dwellers prefer more government because they "need" more; country folk feel less "need" for government because they don't rub up against each other as much as city dwellers.
Thus the ultimate argument for devolution: Push government functions to the lowest practical level and allow citizens to express their preferences by voting with their feet.
(Thanks to Patrick Cox at Tech Central Station for the maps.)