When examining the economic realities in Mexico, it's not hard to see why the United States has such allure. More than half of the Mexican population lives below the poverty line. Per-capita income is roughly one-third of that in America. And while unemployment hovers at approximately 5 percent, underemployment runs as high as 25 percent.

Examine the economic realities in the United States, and it's equally easy to see why hiring illegal immigrants happens so frequently. In industries such as agriculture, domestic services, construction and restaurants/hotels, it's difficult to find American workers willing to perform all the jobs. The supply of undocumented aliens is seemingly endless, with more than 1 million entering the country every year. As minimum wage laws don't apply, they work for appreciably less. And, provided the employer doesn't get caught, there's no need for payroll taxes such as Social Security, Medicare and other withholdings.

Build a fence on the border as high or as wide as you'd like, there's no stopping the law of supply and demand. Threatening the illegal immigrant with deportation or even imprisonment doesn't help either. The risk-reward computation is skewed heavily toward reward, as the "land of opportunity" offers a better life. The economic and educational resources we have are the envy of the world. Throw in freedom, and the risk factor barely registers.

Which is why we always have asserted the only effective way to reduce the number of illegal immigrants in this country is to target employers.

This week, we finally heard similar sentiment from somebody who can make it happen: U.S. Attorney Barry Grissom.

"If nobody is employing undocumented workers, then we don't have an illegal immigration issue to deal with," Grissom said after his office announced a settlement with a Kansas company that pleaded guilty to accepting fraudulent identification as proof of their employment eligibility.

The company, McCalla Corp., operates six McDonald's restaurants in the Wichita area. In a settlement announced Tuesday, McCalla will pay $400,000 for having employed between 20 and 30 undocumented workers between 2009 and 2012 -- including managers at five of the restaurants.

"We know these practices are widespread," Grissom said, "and investigations similar to the McCalla case are under way."

In September, the U.S. Attorney's Office charged the owners of two Clarion hotels in Kansas City and Overland Park after finding half of their employees were illegal immigrants. If convicted, the owners face losing their hotels, bank accounts and potentially decades in prison.

We applaud the efforts of the Justice Department. Lamentable is the reason behind them: cost-effectiveness. Budgetary constraints have forced the office to stop showing up at job sites and arresting individuals -- who are replaced by other illegal immigrants rather quickly.

Whatever it took to get to this tactic, however, it is the correct course. Economic models point out that disrupting supply simply will result in the creation of a different source. Eliminate demand and the supply channels simply wither away.

Kansas employers should take heed. If undocumented workers are being used to make goods or supply services, business owners no longer merely are running the risk of losing employees. They're running the risk of losing their business.

Editorial by Patrick Lowry

plowry@dailynews.net