It was the first sweep by the U.S. in an opening session since 1975 at Laurel Valley, and gave the hosts a perfect start in their quest to end a run of eight defeats in the past 10 editions.
"It's a good start," U.S. captain Davis Love III told reporters after a chilly, overcast morning at Hazeltine gave way to bright afternoon sunshine.
"But it's long way to go. There's a lot more points out there. Keep doing the same thing over and over every session."
Thunderous roars of "USA, USA, USA" echoed across the ultra-long Hazeltine National layout as twice major winner Spieth and fellow young gun Reed beat European heavyweights Justin Rose and Henrik Stenson 3&2 in the top match to secure the first point.
Olympic champion Rose and British Open winner Stenson went 3-0 when paired together at Gleneagles two years ago and they were sent off first by captain Darren Clarke in a bid to give Europe a fast start.
"Any time you are take on Rose and Stenson, it's never simple," Reed, who sank an 18-foot birdie putt at the par-five 16th to seal the win, told reporters. "We had a great game plan coming in, we stuck with it.
"Just hit a lot of greens. In alternate shot you have to do that, give yourself opportunities. And we were lucky enough to be able to hit a lot of greens and have good looks."
Soon after, U.S. Open champion Dustin Johnson and Matt Kuchar completed a 5&4 demolition of an out-of-sorts Lee Westwood of England and Belgian rookie Thomas Pieters in the anchor match with massive galleries cheering them all the way.
PGA Championship winner Jimmy Walker and Zach Johnson came from one down after 11 holes to beat Spaniard Sergio Garcia and Germany's Martin Kaymer 4&2 before Phil Mickelson and Rickie Fowler delivered the most surprising point of the morning for the Americans.
Fan favourites Mickelson and Fowler were wayward off the tee for most of the session and trailed Northern Ireland's Rory McIlroy and Englishman Andy Sullivan by two after 14 holes before scraping through a fluctuating contest to win one-up.
"All points are big here," said Mickelson, 46, competing this week in his 11th Ryder Cup. "This is a match I felt more pressure than any other Ryder Cup.
"But Rickie was able to get the best out of me and I hit some good irons. We showed a lot of heart to win that match."
The U.S. have lost the Ryder Cup at home just four times since the matches began in 1927, and are bidding to end a run of three successive defeats in the competition.
(Editing by Tony Jimenez/Andrew Both)
