This article is the substance of a report, submitted to the Board of the British Library in 1974, on a short visit to research libraries in the United States made in October and November 1973. The author was at that time in charge of the United States Collection and Superintendent of the North Library in the British Library Reference Division (formerly the British Museum Library); the primary purpose of his visit was to see what implications for the British Library the American situation might seem to suggest. The opinions expressed are, of course, those of the author only, and not of the Board. The original report was prefaced by a detailed acknowledgement of the great hospitality, kindness and co-operation that the author received throughout his visit, and he is glad of this opportunity to express his gratitude publicly, though necessarily less specifically.