American libraries began to be developed in the middle of the nineteenth century and were among the world’s most prominent a century later. The remarkable history of the major libraries in North America, their European models and their strong and innovative leadership is reported here in more or less chronological sequence from the earliest efforts to about 1970, when the unprecedented growth came to an end. The building of the international library collections could not have been achieved without the enterprising efforts of many booksellers in England and on the European continent. Among those who made significant contributions, were three booksellers from the Netherlands: Frederik Muller, Martinus Nijhoff and Swets & Zeitlinger. This article describes their role, but concentrates on Martinus Nijhoff, publisher and bookseller of The Hague, who had by far the longest successful tenure in supplying American libraries with European books and periodicals. Between 1853 and 1971, three generations of the Nijhoff family – Martinus, Wouter and Wouter Pzn –, with their staff members, built one of the leading international publishing and bookselling houses in the Netherlands. Their legacy is permanently embedded in the collections of the great North American libraries.