While winning the final three games of a four-game series, the Nationals outscored the Rockies 42-21.
"You know you're going to score a lot of runs here," Nationals manager Dusty Baker said, "but I didn't have any idea we were going to score that many."
The 11-run inning was the biggest in Nationals history and the most runs in franchise history since the Montreal Expos scored 13 runs in the sixth inning at San Francisco on May 7, 1997.
Winners of 10 of their past 11 games, Washington improved to 16-6, the best start in Nationals history. The Nationals concluded a 9-1 road trip, giving them the best winning percentage in a road trip of 10 or more games in franchise history.
The Nationals sent 15 batters to the plate in their seventh-inning outburst, which included eight hits and three walks and made the score 15-2. Murphy and Adam Lind each had two hits in the uprising.
Eaton scored the first run when first baseman Mark Reynolds snared Harper's hard grounder, scrambled to his feet and threw the ball in the Nationals dugout.
Carlos Estevez, who began the inning on the mound for Colorado, then yielded three consecutive hits, including a double by Murphy and a single by Lind that netted runs. Estevez intentionally walked No. 8 hitter Wilmer Difo to get to Nationals pitcher Gio Gonzalez but walked him to force in a run. It was the third time in three games the Rockies walked a Nationals pitcher.
Jordan Lyles came on and forced in a run with a bases-loaded walk to Eaton, then gave up a two-run single to Trea Turner and Harper's eighth home run, a three-run shot off the back wall of the Rockies bullpen in right-center that went an estimated 451 feet. Murphy singled and scored on Lind's double.
"We scored 11 runs in an inning, and at any point during that inning, somebody could've shut it down," Turner said. "Nobody wanted to make that last out. Nobody wants to give an at-bat away."
Harper was the only player in the lineup without a hit before he walloped his massive home run, his first in 15 plate appearances in the series. He is batting .418 with 25 RBI, a .535 on-base percentage and an .823 slugging percentage during a memorable April.
"It's not over yet, but he's been unbelievable," Baker said. "We were pulling for Harp. It's rare that a power hitter comes here without hitting at least one home run. So it was like, 'Man, Harp's due.'"
Gonzalez (3-0) gave up two runs and seven hits in 6 2/3 innings. He never retired the side in order but ended the third and fourth with double-play grounders. He got 12 outs on ground balls.
"Gio threw a great game, especially here in this ballpark," Baker said. "He threw up some timely double plays and he made quality pitches. And that's how you get out of trouble."
In addition to his bases-loaded walk in the seventh, Gonzalez put the Nationals ahead 4-2 when he singled home a run in the sixth after going 0-for-12 to start the season.
Rockies starter Antonio Senzatela (3-1) gave up a career-high four runs on seven hits and three walks with one strikeout in six innings. Eaton drove one of Senzatela's rare changeups into the right-field stands for his second homer, giving the Nationals a 3-2 lead.
Senzatela issued consecutive walks in the second, followed by Difo's run-scoring double. And Senzatela gave up a leadoff double in the third to Turner, and two groundouts led to another run.
"I saw just one bit of frustration, maybe two, on a couple borderline pitches," Rockies manager Bud Black said of his rookie pitcher. "But he hung in there. They scratched him for a couple runs, and he gave up that one long ball. But 4-2 in the sixth with four at-bats to go, he gave us a legitimate chance to win the game, he really did."
That chance was obliterated by the Nationals' record inning at the expense of Estevez, whose ERA ballooned to 9.64, and Lyles, whose ERA jumped to 9.28. Estevez was charged with seven runs in two-thirds of an inning, and Lyles allowed four runs in 1 1/3 innings.
The Rockies' bullpen, which allowed 20 runs in the first 19 games, was torched for 25 runs in the past three games.
"We went through some guys this series," Black said. "The innings, for me, don't matter. It's the number of pitches certain guys threw that might tax them. There were high pitch counts, and that's a little bit of concern. We'll keep an eye on their arms. We'll be all right. We keep eight guys (in the bullpen) for a couple different reasons."
NOTES: Rockies CF Charlie Blackmon extended his hitting streak to 12 games, two short of his career high. ... Nationals RHP Stephen Strasburg was activated from paternity list and will start Saturday against the Mets. ... Washington LHP Matt Grace was optioned to Triple-A Syracuse. ... Nationals 1B Ryan Zimmerman and 3B Anthony Rendon were rested. ... Rockies 1B Ian Desmond (fractured left hand) will go to extended spring training and play there Friday and Saturday. He could be reinstated Sunday. ... Colorado INF Pat Valaika made his first career start in left field and his second appearance at that position. He played one inning there Tuesday. ... Rockies RF Carlos Gonzalez was given a planned day off.