Continuing with the historical priority battle among the older and grander linguistics departments of the USA: naturally, the University of Chicago was bound to respond sooner of later to Berkeley's suggestion of a 1901 founding date. Jason Merchant has written to tell me Michael Silverstein wrote up a history of the department, which Jason has stashed in PDF form here. It provides grounds for pushing back as far as 1892, which would kick the shibboleth out of Berkeley's date; it isn't even in the same century. Some highlights follow (and I'm just repeating what Jason put in his email to me).
Carl Darling Buck was the first linguist on campus, already at the founding of the University in 1892, in the monosomic "Department of Sanskrit and Indo-European Comparative Philology", also known by its short title, the "Department of Comparative Philology".
In 1915, the department's name was changed to "Department of Comparative Philology, General Linguistics, and Indo-Iranian Philology", marking the first appearance of the term linguistics in the departmental name.
Edward Sapir joined the University in 1925, where his courses were listed under the department's rubric. Leonard Bloomfield (who completed his PhD at Chicago in 1909) joined the University as "Professor of Germanic Philology" in 1927 and is listed, along with Sapir, Buck, and another, as one of the "Officers of Instruction" of the department.
The department retained its tripartite name until Buck's retirement in 1934, after which it was known simply as the "Department of Linguistics", when Leonard Bloomfield became its chair.
So, depending on exactly which criteria one wished to apply (sort of like determining what the tallest building in the world is), one could make an argument for any of three dates, it seems: 1892, 1915, or 1934. But it is significant that the current department has a continuous administrative history, with changes only in personnel, focus, and name, from the beginning of the university. At no time was the Chicago department the same as, or a part of, the departments of anthropology or sociology; nor was the department ever closed or subsumed in some other department.