…from a purely economic perspective, illegal immigration is arguably preferable to legal immigration. …the illegal route is for the moment vastly more efficient than the cumbersome legal system. Illegal immigration responds to economic signals in ways that legal immigration does not. Illegal migrants tend to arrive in larger numbers when the U.S. economy is booming and move to regions where job growth is strong. Legal immigration, in contrast, is subject to bureaucratic delays, which tend to disassociate legal inflows from U.S. labor-market conditions. The lengthy visa application process requires employers to plan their hiring far in advance. Once here, guest workers cannot easily move between jobs, limiting their benefit to the U.S. economy.