That 'great, great wall' and those deportations will be costly

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A security contractor frisks a detainee ahead of a deportation flight to Honduras.

In his speech to a joint session of Congress, Trump repeated his long-standing pledge to ramp up deportations of the estimated 11 million unauthorized immigrants in the U.S.

"We will soon begin the construction of a great, great wall along our southern border," Trump said Tuesday night to enthusiastic applause. "As we speak tonight we are removing gang members, drug dealers that threaten our communities and prey on our very innocent citizens. Bad ones are going out as I speak and as I promised throughout the campaign."

As Trump widens the effort to deport millions of undocumented immigrants, though, the true cost of such an undertaking is coming into sharper focus.

Until there are more details of the plan, much of which will require congressional approval, estimates are sketchy. But by any full accounting, the fiscal and economic costs would be huge.

The Trump administration recently backed off earlier pledges to deport anyone in the country illegally. After he met with Mexican officials, Homeland Security Secretary John Kelly said Thursday "there will be no mass deportations."

Still, the Trump administration also this week directed government agencies to begin rounding up and deporting anyone in the country illegally, whether or not they have committed serious crimes.

If the U.S. would seek to remove the entire 11 million or so undocumented workers, it would cost upwards of $500 billion, according to one estimate. It could also wipe out a chunk of the American economy roughly the size of the annual gross domestic product of Texas.

The new Trump initiative includes hiring thousands of new immigration agents, building new detention centers and constructing a southern border wall that was a centerpiece of Trump's election campaign.

Breaking down deportation costs

Last March, American Action Forum, a center-right policy institute led by former CBO director Douglas Holtz-Eakin, estimated it would take $100 billion to $300 billion to arrest and remove "all undocumented immigrants residing in the country, a process that we estimate would take 20 years."

Once those undocumented immigrants were removed, it would take another $315 billion in higher enforcing costs to stop them from coming back, according to the forum.

That estimate includes just the hard cost of removing undocumented workers; it doesn't take into account the economic impact that would result from the removal of some 11 million people from the labor force and the resulting loss of consumer spending.

The forum estimated the removal of that many people would shrink the pool of U.S. workers by 6.4 percent, which means that 20 years from now, the U.S. economy would be nearly 6 percent smaller.

That works out to a loss of $1.6 trillion in lost wages, spending and other economic activity.

To put that in perspective, the gross domestic product for Texas last year was about $1.5 trillion, second behind California.