Under the El Paso program, begun in mid-2017, adults who crossed the border without permission – a misdemeanor for a first-time offender – were detained and criminally charged. No exceptions were made for parents arriving with young children. The children were taken from them, and parents were unable to track or reunite with their children because the government failed to create a system to facilitate reunification. By late 2017, the government was separating families along the length of the U.S.-Mexico border, including families arriving through official ports of entry.
On May 7, 2018, the U.S. Department of Justice (DOJ) announced it had implemented a “zero tolerance” policy, dictating that all migrants who cross the border without permission, including those seeking asylum, be referred to the DOJ for prosecution. Undocumented asylum seekers were imprisoned, and any accompanying children under the age of 18 were handed over to the U.S. Department of Health and Human Services (HHS), which shipped them miles away from their parents and scattered them among 100 Office of Refugee Resettlement (ORR) shelters and other care arrangements across the country. Hundreds of these children, including infants and toddlers, were under the age of 5.
Prior to the Trump administration, families were generally paroled into the country to await their immigration cases or detained together.
via Family separation under the Trump administration – a timeline | Southern Poverty Law Center