Since the Mexican American War of 1846, newspapers large and small have turned to the Associated Press for reporting from places inaccessible to their own reporters.

With more than 200 bureaus around the globe, the AP remains the biggest brand name among what came to be known as the wire services, transmitting its articles and images to news outlets for a licensing fee. Some smaller papers came to rely so heavily on its content that “AP” was its single most frequent byline.

But now, two major American newspaper chains have said they will no longer use the AP for news. Gannett, the publisher of USA Today and more than 200 local newspapers, and McClatchy, which publishes the Miami Herald and The Kansas City Star among more than two dozen other newspapers, said this week that they were ending their content relationship with the AP.

In memos to staff and public statements, executives with both companies described it as a cost-saving move — in the “millions” of dollars, according to McClatchy brass — and said they will have no trouble filling the news gap.

“We create more journalism every day than the AP,” Gannett executive Kristin Roberts said in a Tuesday memo obtained by the Wrap.

But some media observers — including staff members at the affected newspapers — warned that the decision will cut off a vital source of reliable reporting that their readers have come to depend on.

“It’s a loss,” Ilana Keller, a content planner and reporter at the Gannett-owned Asbury Park Press in New Jersey, told The Post. “As our reporting staff got smaller and smaller, we relied more and more on wire services to help fill in the gaps, and losing that is incredible.”

In an emailed statement, AP spokeswoman Nicole Meir said the news service hopes Gannett and McClatchy will continue to use its content news services and that conversations with both chains are ongoing, suggesting the publishers’ decisions could be part of a contract negotiation strategy.