Nowhere is this more evident than with the sister cities of Brownsville and Matamoros, facing each other across the Rio Grande river. Demographically and economically they have much in common: the 2010 Census indicates that over 85% of Brownsville's population is of Mexican ancestry and Spanish-speaking, and although Brownsville is wealthier than Matamoros, it is very poor by American standards, having recently replaced McAllen as the poorest city in the nation. The Mexican state of Tamaulipas, by contrast, is wealthier than the Mexican average.
|Matamoros at left, Brownsville at right. From Google Maps.
A typical house lot in a newer neighborhood of Matamoros has only around 1200 square feet, while in Brownsville, new subdivisions have lots around 5400 square feet. Interestingly, the lot size trends appear to be diverging: Matamoros' new lots are smaller than those in older parts of the city even as car ownership has soared, while Brownsville's are much larger. Older areas of both cities, dating back to the late 1800s or early 1900s, both tend to have house lots of around 3,000 square feet, although in different configurations (Matamoros, for instance, never used rear alleys).
|Contemporary subdivision street in Brownsville. Google Maps.
|Mexican "snout house" in Matamoros, expanded from the developer's
original house of the type still visible to the right. Google Maps.
This fundamental difference in lot size has major implications for the size of the urban area. Matamoros, with a 2010 population of 489,000, actually occupies slightly less area (28 sq. mi.) than Brownsville's 175,000 (29.9 sq. mi.), based on a mapping out of residential urban boundaries in each case. It also must have some implications for home prices: while Brownsville homes are much cheaper than the American average with a median home price of $130,000 for what is typically a three bedroom home, a relatively large Matamoros starter home (915 square feet over two stories on an 1130 square foot lot) can be had for only $34,000. The tiniest of the starter homes, no bigger than a studio or micro-apartment, are as little as $10-15,000. This suggests that a new two-bedroom home in Matamoros can be purchased for approximately what the down payment would be for a typical three bedroom home in Brownsville, and helps explain Mexico's very high homeownership rate. Finally, it has implications for mixing of uses, since the dense packing of houses allows for businesses to thrive on foot traffic, reducing the political pressure for parking minimums that would, even in the absence of zoning, effectively ban businesses on tiny lots.
The economic, financial, geographic, historical, cultural and legal factors that have led to such divergent patterns of urban growth aren't easily or quickly summarized, but the different outcomes are clear enough.
Related posts: Check out Apex Urbanism, which has a series of posts featuring various Mexican cities.