Everything from new cars to computers to fresh fruit swells the free-trade flow along the United States-Mexico border. But one item of cross-border commerce that probably deserves more notice is that most basic byproduct of North American prosperity: trash.
Mexicans are rapidly picking up the slack left by a declining Asian market for US recyclables. Plants in Mexicali and Monterrey, Mexico, gobble up everything from glass beverage bottles to waste paper to plastic throwaways to mineral-rich dust from US steelmaking furnaces.
The flow defies exact measure. But The Wall Street Journal recently reported that last year Mexico imported between $500 million and $1 billion in trash from its northern neighbor. Mexico's waste-paper intake, for example, has nearly doubled since NAFTA began in 1993, to well over 1 million tons yearly.
New bottles, packing materials, and even sorted high-quality plastic scrap then flows back northward. It's hardly NAFTA's mainstream. But it is an example of freer trade serving both societies - and helping, not threatening, the environment.