The revenue from paid subscriptions also more than doubled to just over $1 billion.
The subscriptions pushed overall revenue growth for the US music industry in the first half of the year up 8.1 percent from a year earlier.
The last time the industry posted a similar rate was in 1999, at the dawn of the era of digital music, when revenue grew 6.4 percent on a full-year basis.
Cary Sherman, chairman and chief executive of the industry association, said that the figures showed that music remained "fundamentally undervalued" due to outdated laws and structures despite rising consumer demand.
"Many services rake in billions of dollars for themselves on the backs of music's popularity but pay only relative pennies for artists and labels. Pirate sites operate with seeming impunity," he said in a blog essay.
Outside of streaming, other segments of the music industry remained soft in the first half.
CD shipments dropped 11.2 percent to 38.9 million, while downloads on iTunes and other services tumbled 14.5 percent to 48.2 million albums.
In one potentially alarming sign, shipments of vinyl albums -- a niche market which has recently led to a resurgence of record stores -- slid 9.1 percent to 8.4 million records.
Vinyl shipments had soared by more than 28 percent in all of last year.
The latest US figures are in line with the global industry, which last year posted its first significant growth since the late 1990s thanks to the rising popularity of streaming.