The Englishman’s effort, which matched playing partner Tiger Woods’ opening round when he won by a record 15 shots on the California coast in 2000, earned him a one-shot cushion over four players.
“Obviously, a fun day of golf,” said Rose, the 2013 winner at Merion. “I guess the round was going nicely. I was three-under-par, had a rough patch, had to scramble, work hard, keep my round together.
“Even when I made a mistake, I was willing to accept. And then got rewarded with a hot finish … [taking] a good round to a great round.”
On a day where the winds were relatively light and the mercury barely crossed the 60-degree mark, the world’s best players took full advantage of their opportunity.
Thirty-nine golfers bettered par, matching the second-most in championship history and just five behind the record 44 recorded two years ago at Erin Hills.
Another former Scottish Open winner, Rickie Fowler, sits a shot behind Rose along with fellow Americans Xander Schauffele and Aaron Wise, as well as South African Louis Oosthuizen.
Scott Piercy and sectional qualifier Nathan Lashley shot 67s, with 2011 winner Rory McIlroy and a pair of recent winners of The Open, Henrik Stenson and Francesco Molinari, headlining a large group on 68.
Two-time defending champion Brooks Koepka and Woods carded 69 and 70, respectively, the latter doing it with 11 one-putts.
The 72.66 stroke average was the lowest for a first round of any of the six U.S. Opens contested at Pebble Beach, nearly two strokes lower than the 74.51 recorded in 1992.
“Thursday is just about getting off to a good start,” said Fowler, who had nine birdie looks of 15 feet or under in his round, which was one stroke off his best US Open effort.
“You can’t go win the golf tournament today, but you can take yourself out of it or put yourself in position where you’re just trying to fight your way back.
“It’s nice when you shoot 66, and that’s about as high as it was going to be. So I’m really happy with where we’re at and looking forward to see if we can keep it going.”
On a day when there were 17 eagles, surpassing the single-day mark of 13 from the first round in 1983 at Oakmont, Masters champion Woods hit nine of 18 greens and had 23 putts - his fewest putts ever in a US Open round.
Norwegian Viktor Hovland, the US Amateur champion, posted the lowest round among the 15 amateurs with a 69.
It was one better than Amateur champion Jovan Rebula, the nephew of two-time US Open winner Ernie Els.