In 1957 composer, conductor, and sideman Gunther Schuller defined the Third Stream as "a new genre of music located about halfway between jazz and classical music." He also defined what it was not. [more inside]
27 live recordings from the 1959 Newport Jazz Festival can be streamed for free at Wolfgang's Vault. Here's a few of the musicians you can listen to: Count Basie & His Orchestra, Dizzy Gillespie, The Modern Jazz Quartet, Oscar Peterson Trio and Thelonious Monk. Registration is required but it's oh so worth it. The New York Times has the backstory of how these recordings ended up at Wolfgang's Vault.