Why it matters: The largest number of single-day arrests announced by Immigration and Customs Enforcement since Trump took office last Monday and declared a national emergency on the U.S.-Mexico border is a clear sign that his administration is stepping up efforts crack down on undocumented immigrants.

The Trump administration launched an immigration enforcement blitz in Chicago on Sunday that includes several federal agencies that have been granted additional authorities to arrest undocumented immigrants in the US,

The number of arrests there was uncertain. Illinois officials, including the governor, said they had not been given advance notice.