This is a stupid, stupid idea. Cities that cross borders are a problem wherever they are, because of the administrative difficulties involved: you can't have a single, consistent set of rules and laws spanning the whole city, you don't have a single government managing it, etc.<p>We already have a LOT of problems here in the US where metro areas are comprised of multiple cities, and worse, cross state boundaries.<p>Ask anyone who lives in one state, and drives to the other state to go to work every day, how they like doing their taxes: it's a nightmare of forms every year because there's multiple taxing authorities they have to answer to.<p>Or look at public transit that crosses state boundaries, such as that used between New York City and New Jersey. It's a mess, because there's no single government that the transit agency has to answer to and is accountable to. Funding is always a problem because again, there's no single government that controls it, and no single electorate that government is accountable to.<p>Even a metro area within a state, but composed of multiple cities can have problems. In the Phoenix metro area, there's confusion at traffic lights because all the cities have leading left turn arrows, <i>except</i> for Scottsdale which has lagging turns. This has caused many accidents because drivers get used to one or the other and then drive across one street and suddenly the standards change.<p>There was an interesting college project back in the 70s called "The 38 States" (google it) where a class decided the current US state borders were badly drawn and led to too much inefficiency, so they came up with a new map of the US with idealized borders, taking into account local cultures and locations of metro areas. One of the prime factors in how they drew the new state borders was to make sure that no metro area spanned two states, and instead the borders were drawn, whenever possible, in rural areas between cities. This guy's idea flies entirely in the face of this.<p>The governments in Oregon and Washington already complain a lot about people living in Vancouver (WA), where there's no income tax, and then doing all their shopping in Portland, where there's no sales tax. Doing this over a national border, between two countries as economically disparate as the USA and Mexico, is a recipe for disaster.<p>Plus, as dogma1138 says, we <i>already have</i> places much like this on the border. El Paso/Cuidad Juarez is a prime example. It isn't a panacea, and last I heard, Juarez had a huge problem with brutal gang violence.