In the absence of outside restraint, Arizona cities will eat everything.
Driving home late yesterday night from a conference in Flagpole, I was reminded by a sign declaring the Phoenix city limits--several miles north of Happy Valley Road--that Arizona law has an absurd quirk which allows cities to annex large amounts of empty land. Phoenix isn't even the craziest example; the sleepy little town of Buckeye is 48 miles wide north-south and 24 miles wide east-west.
Arizonans have, as a rule, fought both incorporation and annexation. Rillito, completely surrounded by Marana, has held out for years. Green Valley has yet to even come close to incorporation. Casas Adobes residents have made it clear that they want to be a part of neither Marana nor Oro Valley nor Tucson; independent incorporation is still a contentious matter. Residents of unincorporated areas receive basic services (protection of law, etc.) from the county and contract privately for the rest (bring that up to anyone who says "libertarianism looks good on paper but doesn't work in life"!); incorporation replaces this market process with political bureaucracy. Living in an unincorporated area does mean that a sizable portion of one's taxes are sent to Phoenix, never to return, but the benefits may nonetheless be outweighed by the costs.
Frustrated in their attempts to seize inhabited areas and expand power and tax revenues, Arizona's municipalities have been moving towards what amounts to preemptive annexation, allowing them to continue to run cities like multilevel marketing or pyramid schemes. Spending like drunken sailors is alright; subsidized growth within the city's wide limits will make the latest bond issue look like chump change in a decade or two when the tax base has doubled!
Growth in Arizona will inevitably continue, and since we have yet to meaningfully reform our water laws and privatize the aquifiers, it will become increasingly irresponsible. Allowing annexation of undeveloped areas sets up an incentive for politicians to encourage such sprawl. Moreover, residents of new development ought to have the choice of being subject to existing city government, their own local government, or none at all. That's a matter of justice, moreover, it keeps the cities honest.
Arizona's annexation law has an obvious flaw, and needs to be reworked again.