The Chronicle of Higher Education recently published a short piece celebrating arXiv's 20th birthday. Excerpts:
. . . . ArXiv, back in 1991 and still today, focuses on physics. “The original plan was for roughly 100 full-text article submissions each year,” writes Mr. Ginsparg, who works at Cornell University. Today the site gets about 75,000 of these “preprints” every year, and it serves up about one million full-text downloads to about 400,000 users every week. It holds roughly 700,000 texts. . . .