The punchlines write themselves
Sombrero-tip to South Texas Chisme for finding this in the Valley Morning Star:
Can the U.S. border fence be built on deadline without the help of foreign laborers?
With 670 miles of the U.S.-Mexico border fence slated for completion by year’s end, construction companies in Texas are questioning the feasibility of completing such a project without immigrant labor.
…
“Is it possible to construct a wall without undocumented workers?” asked Perry Vaughn, executive director of the Rio Grande Valley Chapter of the Associated General Contractors of America. “It’s probably borderline impossible to be honest with you.”
…
In the late 1990s, the Golden State Fence Co., a fence-building company in Southern California, hired undocumented immigrants to build millions of dollars’ worth of fencing between San Diego and Mexico.
The company received several warnings, but federal agents found undocumented workers still on the job in 2005.
In 2006, the company agreed to pay $5 million and its executives pleaded guilty to hiring undocumented immigrants.
mexfiles.net 
Too many dumb Christians in the US that don’t understand true free trade are scared of the North American Union and the “Nafta” Super Highway” to allow an open border and free movement of goods and people.
Then again, why does Mexico guard their Southern Border? After all, those people south of the Yucatan speak Spanish as well. Unless of course they are trying to keep English, Dutch, and Portuguese speakers out of Mexico?
Maybe Mexico should quit pandering for an open US-Mexico border and open both of theirs up. Either way, both Mexican voters, American Voters, as well as those in Canada are all paranoid that they will all start mixing together! Oh no!