Cool jazz is a jazz style that emerged in the late 1940s in New York City.
In 1946, after the Second World War, there was an influx of Californian (predominantly white) jazz musicians to New York. Once there, these musicians mixed with the mostly African-American bop musicians. The product, cool jazz, was a lighter, more romantic style of jazz than bop; cool jazz took a relaxed, simple approach to rhythm while preserving the harmonic ideas of bop. The Claude Thornhill Orchestra with the arranger Gil Evans recorded cool jazz as early as the late 1940s; Thornhill's most popular song, "Snowfall", is still played today. Other cool musicians of the 1940's included Lennie Tristano and his colleagues Billy Bauer and Warne Marsh. The style grew more prevalent in the 1950's, attracting the attention of musicians like Miles Davis, whose recordings Birth of the Cool (1957) and Kind of Blue (1959) became among the most popular jazz albums ever produced.