01/30/2013 01:22 pm ET Updated Apr 01, 2013

Borderline Wrong

Building a wall to keep people away is a deep-seated human instinct. The Great Wall of China emerged more than 2,000 years ago as a defense against nomadic raiders. Hadrian's Wall was built in northern England, beginning in 122 C.E., to protect the northern frontier of the Roman Empire.

So the current focus of the American public and policy makers on U.S. border security and immigration law enforcement as the most important and urgent component of immigration reform has a long history.

But that doesn't mean our attempts are always well-informed or effective.

A new report from the Migration Policy Institute finds that the United States "spends more on immigration enforcement than on FBI, DEA, Secret Service and all other federal criminal law enforcement agencies combined." Immigration enforcement spending was $18 billion in 2012 and has been $187 billion over the past 26 years during the decades of increased immigration and border enforcement.

About 21,000 Border Patrol agents now operate motion sensors, aerial drones, radiation monitors, and other technological resources -- all with the aim of fulfilling the public's goal of controlling the border.

But during most of the immigration enforcement buildup, unauthorized immigration surged alongside spending. It peaked around the year 2000, with the Border Patrol reporting 1.7 million apprehensions.

Since then, unauthorized immigration slowed and then fell. While increased immigration enforcement played a role in the decrease, most experts cite the lack of jobs in the U.S. economy and improved economic conditions and demographics in Mexico as the major reasons for the drop in undocumented immigration.

The evidence indicates that border enforcement will probably never be totally effective in stopping unauthorized immigration no matter how much we spend.

In spite of the public's demand to seal the border, up to half of all unauthorized immigrants don't sneak across, under, or over the border -- they drive through it or fly over it legally -- arriving in the United States with a valid visa, which they then overstay.

In 2006 the Pew Hispanic Center estimated that 45 percent of all unauthorized immigrants arrived in the United States with a legal visa. Of course, no amount of border enforcement will impact this group of unauthorized immigrants.

Most unauthorized immigration is driven by jobs. Historically, Latin American immigrants come to the United States because of the poverty and lack of job opportunities in Mexico and Central America and the abundance of low-skill jobs in the United States. For immigrants who do enter the country illegally, the deprivation they face at home means that if there's a job in the United States, they'll find a way to get here.

Instead of continuing to focus almost exclusively on border enforcement -- a strategy with a marginal payoff -- the following realities should guide policy makers:

1) Over the long term, less poverty and economic inequality in Mexico and Central America will generate fewer unauthorized immigrants. The United States should target international development assistance that provides economic opportunities in the regions sending immigrants so that fewer people feel that they must leave to feed their families.

2) An immigrant worker program that allows foreign workers to come to the United States would help meet the labor force needs of the rebounding U.S. economy without relying on illegal entries. A program that respects the rights of workers and the labor needs of U.S. employers could have benefits for the nations sending immigrants, for the workers, and for the U.S. economy.

Most Americans want a humane and fair immigration system. Border and immigration enforcement certainly has an important place in immigration reform discussions. But a continued focus on a border-enforcement-only policy is neither cost-effective nor humane.

Update: This article was edited to clarify that any immigrant worker program must respect their labor rights.