All bolds mine

New York Times, December 16, 2006:

Immigrant families scrambled yesterday to find detained relatives, arrange care for children of deported parents and recover from the loss of work as a result of raids this week by immigration authorities at meat-packing plants in six states. [...] In all, 1,282 legal and illegal immigrants were arrested, and in most cases the plants, all operated by Swift & Company of Greeley, Colo., were the largest employer around.

Star Tribune (Mineapolis-St. Paul, Minnesota) December 13, 2006:

...[I]n Worthington, a city of 12,000 in the state's southwestern corner, the raid spread panic in homes and schools, where about 39 percent of the students are Hispanic and many are children of Swift workers. [...] Schools Superintendent Steve Joel said the parents of 1,100 students work at the meatpacking plant, and the effect on the children is potentially huge.

Washington Post December 15, 2006:

Both Swift and its employees -- who bore the brunt of the punishment -- are caught in an economic bind far bigger than themselves. Meat processing is dirty and dangerous. Fewer and fewer members of the increasingly educated American workforce are interested in the jobs. As a result, although it now pays an average of $13 an hour, or $25,000 a year, the industry increasingly relies on foreign workers, not because they're cheap -- $25,000 a year is what trained paramedics and college-educated kindergarten teachers make in meatpacking states such as Iowa and Kansas -- but simply because they'll do the work. If immigrants weren't available, companies such as Swift would have to close, and both meatpacking and the agriculture that depends on it -- cattle and hog producers -- would eventually move to other countries. Not only that, but U.S. law makes the bind much worse for both employers and employees. Despite the meatpacking industry's well-known need for foreign labor, the United States offers virtually no way for these workers to enter the country legally. Every year the economy as a whole creates some 500,000 more unskilled jobs than Americans want to do, yet we issue only 5,000 year-round visas for the immigrants who might fill them. For companies such as Swift and its workers, there's no good answer, and it's not surprising that many break the law.

(You be the judge of how relevant these final clips may be.)

Halliburton website, press release dated January 24, 2006:

The contract, which is effective immediately, provides for establishing temporary detention and processing capabilities to augment existing ICE Detention and Removal Operations (DRO) Program facilities in the event of an emergency influx of immigrants into the U.S., or to support the rapid development of new programs. The contingency support contract provides for planning and, if required, initiation of specific engineering, construction and logistics support tasks to establish, operate and maintain one or more expansion facilities.

Wikipedia on Habeas Corpus:

The November 13, 2001 Presidential Military Order gave the President of the United States the power to detain non-citizens suspected of connection to terrorists or terrorism as an enemy combatant. As such, that person could be held indefinitely, without charges being filed against him or her, without a court hearing, and without entitlement to a legal consultant.

Presidential Military Order, November 13, 2001:

The term "individual subject to this order" shall mean any individual who is not a United States citizen with respect to whom I determine from time to time in writing that: (1) there is reason to believe that such individual, at the relevant times, (i) is or was a member of the organization known as al Qaida; (ii) has engaged in, aided or abetted, or conspired to commit, acts of international terrorism, or acts in preparation therefor, that have caused, threaten to cause, or have as their aim to cause, injury to or adverse effects on the United States, its citizens, national security, foreign policy, or economy; or (iii) has knowingly harbored one or more individuals described in subparagraphs (i) or (ii) of subsection 2(a)(1) of this order; and (2) it is in the interest of the United States that such individual be subject to this order.

My point in including the text of the Order was actually to point out that the individuals to whom it applies are, quite literally, anyone to whom George W. Bush says it applies, and that "harm to the economy" (taking American jobs?) is among the justifications.

However, given the economics of immigrant labor in the United States, it's also true that the raids themselves - if they succeed in removing illegal immigrant labor from the workforce, will inevitably have "adverse effects" on the United States economy - see particularly the Washington Post article linked above, and consider what would happen to food and construction prices if willing suppliers of cheap labor were no longer available.

Of course, it would be ludicrous to suggest that the immigrants taken in the raids have any connection to or intent to harm the economy through an "act of international terrorism," which is why I imagine many people would consider these last clips irrelevant to the immigration raids.

I mean, it's not like the immigrants have weapons of mass destruction or anything.