A letter written by Abraham Lincoln is addressed only to "my dear Sir" and has a small section clipped out of it—but why? Researchers at the Papers of Abraham Lincoln project investigated the letter in which the president asks an ally to keep an eye on a possible supporter in the 1860 election, the AP reports. Lincoln asks the recipient to "keep up a correspondence" with a man whose name was cut out, because "I like to know his views occasionally." That phrase—"keep up a correspondence"—is what unraveled the mystery. Running the words through their searchable database, historians at the Papers of Abraham Lincoln identified the letter's recipient as one Leonard Swett.
That same phrase appeared in a previous letter Swett—an attorney and fellow Republican from Bloomington, Illinois—wrote Lincoln, in which Swett shared the details of his correspondence with "our friend TW of Albany." TW is likely Thurlow Weed, New York state political boss and Republican newspaper editor. Lincoln wanted Weed's backing in New York, but Weed preferred William Seward for the Republican nomination. Lincoln would end up winning Weed's support and making Seward secretary of state. "To be able to identify the date, recipient, and subject of such a brief letter is a remarkable achievement," said the director of the Papers project—where a half dozen volunteers are busy inputting nearly 200,000 documents into "aged computers" in Springfield, Illinois, the Chicago Tribune reports. (Click to read about another mysterious Lincoln letter.)