Answer by taking a quote from the following article:

Andrew Carnegie ( kar-NAY-gee, but commonly  KAR-n@-ghee or  kar-NEG-ee; November 25, 1835 - August 11, 1919) was a Scottish-American industrialist, business magnate, and philanthropist. Carnegie led the expansion of the American steel industry in the late 19th century and is often identified as one of the richest people (and richest Americans). He became a leading philanthropist in the United States and in the British Empire. During the last 18 years of his life, he gave away about $350 million to charities, foundations, and universities--almost 90 percent of his fortune.

Among his many philanthropic efforts, the establishment of public libraries throughout the United States, Britain, Canada and other English-speaking countries was especially prominent. In this special driving interest and project of his he was inspired by meetings with philanthropist Enoch Pratt (1808-1896). The Enoch Pratt Free Library (1886) impressed Carnegie deeply; he said, "Pratt was my guide and inspiration".  Carnegie turned over management of the library project by 1908 to his staff, led by James Bertram, (1874-1934). The first Carnegie library opened in 1883 in Dunfermline. His method was to build and equip, but only on condition that the local authority matched that by providing the land and a budget for operation and maintenance. To secure local interest, in 1885, he gave $500,000 to Pittsburgh for a public library, and in 1886, he gave $250,000 to Allegheny City for a music hall and library; and $250,000 to Edinburgh for a free library. In total Carnegie funded some 3,000 libraries, located in 47 US states, and also in Canada, Britain, Ireland, Australia, New Zealand, South Africa, the West Indies, and Fiji. He also donated PS50,000 to help set up the University of Birmingham in 1899.  As Van Slyck (1991) showed, the last years of the 19th century saw acceptance of the idea that free libraries should be available to the American public. But the design of the idealized free library was the subject of prolonged and heated debate. On one hand, the library profession called for designs that supported efficiency in administration and operation; on the other, wealthy philanthropists favored buildings that reinforced the paternalistic metaphor and enhanced civic pride. Between 1886 and 1917, Carnegie reformed both library philanthropy and library design, encouraging a closer correspondence between the two.

Did he give any more money for libraries?
he gave $250,000 to Allegheny City for a music hall and library;