U.S. immigration officials could soon make it much more expensive for some Americans to research their family tree.

Under a proposal from U.S. Citizenship and Immigration Services (USCIS), a federal agency, the fee to retrieve older citizenship, visa application and other records for deceased relatives could soar as much as 380%, to $625 for a single paper file. It now costs $130.

The proposed fee hike involves a USCIS program that lets family members, genealogists and others obtain information about ancestors who came to the U.S. between the late 19th and mid-20th centuries.

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Professional and amateur genealogists are decrying the plan, saying it could deter families from learning about deceased relatives. Such research has become ""a huge hobby for many," said Rich Venezia, a professional genealogist who teaches courses on how to obtain USCIS records.

"I've twice gotten truly valuable information from these records I could not find anywhere else," Baltimore journalist and genealogist Jennifer Mendelsohn said by email. "In one case, we learned a long-buried family secret — that my great-grandfather had been involved in a fencing operation and was arrested for grand larceny, though the charges were later dropped."

"Highway robbery"

Just over a decade ago, it cost $20 to search a federal index and another $20 or $35 to obtain records, depending on whether it was held on microfilm or paper, on immigrants born as late as the mid-1950s. Three years ago, in 2016, the fees climbed to $65 for an index search and another $65 for the record itself, or $130 in total.

Venezia is leading a campaign to convince the agency to withdraw the fee hike before a window for public comment closes Dec. 30. "They are America's records, created by our ancestors and paid for by fees from our ancestors," he said.

"We're happy to pay fees, but who is going to pay $625 a pop, especially when 20 years ago it was available under the [Freedom of Information Act,]" Venezia added.

"I don't believe that historical records should be a revenue stream. We understand there may be processing costs associated with retrieving them, but this is highway robbery," said Mendelsohn, who founded the "Resistance Genealogy" project that digs up historical information on politicians and others opposed to immigrants.

The fee hikes come the growing popularity of websites and services that cater to those looking to delve into their family tree. Among the best-known, Ancestry.com, has more than 3 million subscribers that pay to prowl its database.

"Ancestry is in ongoing conversations with the U.S. Citizenship and Immigration Services to offer our support in making their record collections more accessible through digitization," a company spokesperson said by email regarding the proposed fee increase.

USCIS did not detail the factors that went into its proposed fee structure. By law, the agency funds its own operations. Among the wide-ranging fee hikes it proposed in November are stiff increases to apply for a green card or citizenship applications. That increase is needed to offset a nearly $1.3 billion annual budget gap, the agency said in a news release.

"USCIS is required to examine incoming and outgoing expenditures, just like a business, and make adjustments based on that analysis. This proposed adjustment in fees ensures more applicants cover the true cost of their applications and minimizes subsidies from an already over-extended system," the agency told CBS MoneyWatch in an email. "Furthermore, the adjudication of immigration applications and petitions requires in-depth screening, incurring costs that must be recovered by the agency, and this proposal accounts for our operational needs and better aligns our fee schedule with the costs of processing each request."