This (likely with a bit more editing/polish) will be in tomorrow’s WOLA Border Update, but it’s also useful as a standalone post:

• March 2020: The Trump administration’s Centers for Disease Control and Prevention (CDC) imposed the measure, at the beginning of the COVID-19 pandemic, as U.S. borders closed to most travel. Citing the difficulty of detaining asylum seekers in congregate settings where viruses could spread, the order—drafted by hardline immigration opponents in the Trump White House, citing an obscure 1940s quarantine law—suspended the right to seek asylum at the U.S.-Mexico border. It ordered CBP to block asylum seekers from approaching ports of entry (official border crossings) and to quickly expel all migrants, regardless of protection needs, apprehended elsewhere. It was later revealed that CDC officials opposed this application of Title 42, but bent under intense political pressure. Mexico agreed to accept land-border expulsions of 4 countries’ citizens: its own, plus those of El Salvador, Guatemala, and Honduras.
• November 2020: D.C. District Court Judge Emmet Sullivan ruled that Title 42 could not be used to expel unaccompanied child migrants. This decision was overturned on appeal in January 2021, just before Joe Biden’s inauguration, but the Biden administration has chosen not to expel non-Mexican unaccompanied children. The Trump administration had expelled unaccompanied kids 15,863 times between March and November 2020.
• January 2021: The Biden administration kept the Title 42 measure in place. Of all Title 42 expulsions since March 2020, at least 81 percent have taken place since Joe Biden’s inauguration.
• August 2021: After negotiations with the Biden administration broke down, the ACLU and other organizations resumed litigation challenging Title 42 in D.C. District Court.
• September 2021: Following a large-scale arrival of Haitian migrants in Del Rio, Texas— notorious for disturbing images of Border Patrol agents on horseback charging at migrants—the Biden administration began a large-scale campaign of aerial expulsions back to Haiti. Witness at the Border would count 229 expulsion flights to Port-au-Prince and Cap-Haïtien between September 2021 and May 2022.
• March 2022: The CDC decided that the pandemic’s reduced intensity made it possible to end Title 42 expulsions. The Biden administration set May 23, 2022 as Title 42’s termination date.
• April 2022: Human Rights First reported tracking “at least 10,250 reports of murder, kidnapping, rape, torture and other violent attacks against migrants and asylum seekers blocked in or expelled to Mexico due to Title 42 since the Biden administration took office.”
• May 2022: Mexico agreed to accept land-border expulsions of Cubans and Nicaraguans for a few weeks, until May 23.
• May 2022: In response to a lawsuit brought by Republican state attorneys-general, Louisiana Federal District Court Judge Robert Summerhays issued a preliminary injunction blocking the Biden administration from lifting Title 42. The May 23 deadline was revoked, and expulsions continued.
• August 2022: For the first time ever, migrants from Mexico, El Salvador, Guatemala, and Honduras comprised less than half of the population of migrants encountered at the U.S.-Mexico border. This was largely because migrants from these countries faced a very high probability of Title 42 expulsion, but citizens of all other countries (especially Cuba, Nicaragua, Venezuela, and Colombia) were more difficult for the U.S. government to expel; most were being released into the U.S. interior.
• October 2022: The U.S. and Mexican governments announced that Mexico has agreed to accept land-border expulsions of citizens of Venezuela.
• November 2022: In the case (Huisha-Huisha vs. Mayorkas) brought by the ACLU and other organizations, Judge Emmet Sullivan struck down Title 42. He acceded to a Biden administration request for five weeks in which to wind down the policy. Republican state attorneys general filed a motion to allow them to intervene in the suit.