ONE of the dumb(er) things the United States Congress did last year was to vote to build a 700-mile double-chain-link fence along the border with Mexico, ostensibly to keep out illegal immigrants.
Never mind that the legislation, signed by President Bush with great fanfare on Oct. 26, was a pre-election stunt by Republicans desperate to stave off the tidal wave of defeat that eventually engulfed them on Nov. 7.
There are many reasons a fence would do little to deter illegal workers from crossing into the U.S., but one fact glossed over amid the hype is that the proposed barrier - 15 feet tall, with "stadium lighting" - would cover only about one-third of the 2,000-mile border with Mexico as it runs along Texas, New Mexico, Arizona, and California.
Putting up a fence would only shift the exodus of illegals to unprotected areas, just as a similar project did in San Diego, Calif., in the 1990s. Moreover, the bill Congress passed contained no money to build it.
Now comes word that the cost of putting up such a barrier would be so prohibitive that even lawmakers who voted for it are having second thoughts, meaning the project may be scrapped.
One of those with doubts is Sen. Kay Bailey Hutchison, Republican of Texas, who conceded to the Dallas Morning News that perhaps Congress wasn't "really in the real world" when it approved the fence.
The Congressional Research Service estimates the cost would be in the neighborhood of $50 billion, a far cry from the $2.1 billion that its backers were claiming.
Meanwhile, lawmakers like Ms. Hutchison are being deluged with complaints from unhappy city mayors and business people who think a fence would be worthless and don't want it built.
The fact is that business interests in the border states depend on illegal immigrants for a big chunk of their labor force. Even President Bush, the former Texas governor, understands that fact of economic life.
A solution to illegal-immigration problems would be a fine achievement for the new Congress. But please, not a fence.