Most of the undocumented immigrants who are in the United States have overstayed a visa and did not cross the border illegally, according to a new analysis from the Center of Migration Studies.

In cities across the country, local activists marched in support of a progressive agenda centered on economic justice, racial justice and immigrant rights.

“We will just do what we need to do to help people in need,” said Antonio Fernandez, C.E.O. of Catholic Charities for the Archdiocese of San Antonio.

The study found Latina immigrant women in Arizona who were pregnant during the contentious S.B. 1070 passage had babies with lower birthweight compared with those in prior years. Average birth weights did not decrease among U.S.-born white, black or Latina women during the same time.

Government investigators said Thursday that thousands more migrant children may have been separated from their families than the Trump administration has acknowledged.