There are millions of records held at the agency, Carl says. These include alien registration files, files for certificates of naturalization, and visa files, if one applied for a visa to come to the United States. "There might be something called a registry file if, during the process of naturalization, the government couldn't find you on a ship manifest, so they were trying to document how you entered the country in the first place," Carl says.
For people trying to trace their family histories, these files can offer critical information, including photos. She says genealogical research goes beyond just wanting to know relatives' names; people want to understand the kind of lives their ancestors lived.
"Sometimes you've never seen a picture of your great-grandfather or your grandfather other than as a grandfather, not as a young person," Carl says. "This gives you a way to understand what their lives were like when you can't ask them the questions anymore."
Even when the files don't contain photos, they almost always include a signature, Carl says, "which is a way to have that human touch in a record."
USCIS documents can be especially important for populations in the U.S. affected by discriminatory immigration laws, Carl says. These groups include Japanese-born residents who were denied citizenship until after World War II and people of Chinese descent who were subject to immigration and citizenship restrictions between the 1870s and the 1950s.
Carl and colleagues have created a website with more information on the files USCIS has, the proposed fees, as well as how to comment.
She says she first learned about the value of immigration documents when doing research on her own family.
"My grandfather came to this country as a child and became a citizen," she says. "But in the 1960s, my grandfather had no idea where his certificate of naturalization was. He wanted a copy of it that had his name on it. And he also needed to prove how old he was to Social Security so he could start collecting his benefits."