On the morning of August 25, 1972, my wife and I were sitting in our car as the line of traffic moved slowly forward toward the Gateway International Bridge at Matamoros, Mexico. Like many Americans coming back into the United States through that southern border crossing, we were looking forward to our return.

A long drive across the flat plains of south Texas would bring us back to Little Rock. We were ready to put Mexico behind us, particularly after some disturbing events over the previous days at our Matamoros hotel.

The apprehension we felt was nothing I could specifically explain. But there was a gnawing discomfort in my neck and shoulders, as if I had been carrying a heavy backpack all day. I drummed my fingers on the Ford LTD's steering wheel as we inched forward, the traffic forming a single line as it approached the solo guard station in use that day. On the other side was Brownsville and the open road home.

As we drew closer, I could see a single U.S. customs official greeting every car with a series of questions. We were four or five cars back in the line, and I was impatiently estimating the time each car might need to get through the gate. I was really ready to get out of Mexico. The customs officer was a short, stocky woman whose brown uniform fit tightly on her barrel-shaped torso. She spoke the same words to each car, took their driver's identification, checked off a series of perfunctory questions, and sent each car through with an impersonal efficiency.