The national debate on U.S. immigration policy isn’t just about whether people who break the law by entering the country illegally should be treated like everyday criminals, it also has to do with money — a lot of money.

This is why, according to the Sunlight Foundation, there are over 3,000 lobbying organizations representing hundreds of private interest groups doling out cash to Washington power players in an effort to ensure their profit interests are included in any reforms.

These interests include giants like Microsoft Corporation (Nasdaq:MSFT) and Google Inc. (Nasdaq:GOOG) that would like to see the annual cap on H1-B visas increased to allow more skilled foreign workers, such as computer programmers, into the country every year. They also include thousands of small businesses in the seafood processing and landscaping industries that rely on an annual pool of foreign temps under the H2-B visa program. Growers, too, have long pushed for more beneficial policies related to their reliance on foreign holders of H2-A visas for their seasonal demand for fruit and veggie pickers.

Private for-profit prisons are also in the game, as reported by The Financial Times.

The reason?

Because thanks to Operation Streamline, a program begun under the Bush administration in 2005 that fast-tracked federal criminal charges against people who enter the country illegally, the prison population has ballooned — which means more profits for private prison companies. They would like to ensure a steady flow of illegal immigrants into their cells.

For example, Nashville-based Corrections Corp of America (NYSE:CXW) – which has seen its stock price gain 171 percent since the start of 2006, leading to two stock splits – has doled out $881,898 in contributions since last year, including donations to immigration-policy hawks like Rep. Hal Rogers (R-Ky.), head of the powerful House Appropriations Committee. Corrections Corp of America (CCA) also began paying dividends last year, which is often done when companies feel they’re on stable enough footing to share profits with their shareholders and encourage them to continue to invest in their businesses.

CCA, the largest private prison operator in the U.S., stated in its 2011 annual report that changes to the way the U.S. treats illegal immigrants, “could affect the number of persons arrested, convicted, and sentenced, thereby potentially reducing demand for correctional facilities to house them.”

The country’s second-biggest private prison operator, The Geo Group, Inc. (NYSE:GEO) of Boca Raton, Fla., echoed similar sentiments deep inside of its 2011 annual report by saying state and federal reform laws could “materially adversely impact us.”

Geo told the Financial Times it has not lobbied Congress on immigration reform and that it has not taken any position on the issue. The company has seen its stock price rocket 343 percent since the start of 2006 following the implenetation of Operation Streamline. The company has since split its stock twice and paid out four dividends last year, including one for $5.68 a share.

Apparently incarcerating people, including illegal immigrants, has been good for both business and the people who invest in private prisons.