Many of them leave the country with their parents. Seventeen each day are referred to the U.S. foster-care system. Others seek out new guardians, American citizens such as Sandigo, to protect their legal interests in the United States. For these children, the arrangement means they can stay in the country where they were born and continue to live with relatives or friends who are in the country illegally, without fear of being taken into state custody.

For Sandigo, it means the file cabinets in her small office are now stuffed with birth certificates, baby pictures, Social Security cards, passports and notarized forms for 812 children living in 14 states, ranging in age from 9 months to 17 years. Only two of the children live with her, and with Sandigo covering some of the costs, the rest stay with friends or relatives. She does this as a volunteer and often at her own expense, not because she considers herself capable of providing a safety net for 812 children but because no one else does it. The federal government doesn’t track what happens to the children of deported parents, and no state or federal officials monitor how many children Sandigo has or how many guardians like her exist in immigrant communities around the country.

Sandigo sees some of the children every week, and others she has met only once, on the day their parents signed the paperwork. “Guardian ad Litem,” the forms are titled, or “Power of Attorney: Care and Custody of Children,” and what follows are four pages of points and sub-points detailing her responsibilities.

“A. To participate in decisions regarding the child’s education . . . ”

“B. To grant permission and consent to the child participating in any activity . . . ”

“C. To make health care decisions . . . ”

“D. To generally do and perform all matters and things . . . ”

On this day, “all matters and things” requires driving her van to Sam’s Club to pick up a few hundred boxes of juice to distribute to children’s homes; and then on to Home Depot to buy an air conditioner for a sweltering, two-bedroom house where three children are now living with a 24-year-old cousin; and then to Party City to get a piñata so she can host a weekend birthday celebration for a 9-year-old whose father was just sent back to Honduras. She raises money through a small charity, American Fraternity, to buy the supplies but ends up paying for most things out of her own savings, built by the nursing-home business she no longer has time to manage. It is dark by the time she returns to her small office in the Miami suburb of Kendall with the familiar feeling that she has forgotten something, or someone. She looks over her to-do list, but every item is crossed off. She checks her phone for messages, but there are none.