By winning their regular-season finale, the Nationals clinched top seeding for the NL playoffs and will open on the road Sunday at the winner of Friday's wild-card game between Atlanta and St. Louis. Game 2 will also be at the wild-card winner's stadium, before the best-of-five series shifts to Washington.
Before Wednesday's game, the Nationals were fitted for hats with postseason patches.
A team from the nation's capital hasn't participated in Major League Baseball action beyond the regular season since the Senators lost the 1933 World Series.
All in all, it was a festive day for the announced crowd of 37,075 and the Nationals (98-64), a club that hadn't finished higher than third place since moving from Montreal in 2005 and twice lost 100 games in a season. This is the first time the Expos/Nationals franchise has finished first in a complete season.
Philadelphia finished third in the division at 81-81, ending a streak of nine straight winning seasons and five consecutive playoff appearances. The nine winning seasons matched the team record set from 1975-83 - the Phillies followed that by going 81-81 in 1984.
Edwin Jackson (10-11) became Washington's fifth pitcher with at least 10 wins, giving up one run and six hits over 6 2-3 innings. He left to a standing ovation, one of several on a muggy afternoon with the temperature in the 70s.
Rookie Tyler Moore's solo shot in the sixth inning made him the seventh member of the Nationals with at least 10 homers this season.
And then, of course, there was Teddy's triumph in the middle of the fourth inning, ending a losing streak that drew attention even from the White House press secretary and Sen. John McCain.
Teddy had lost more than 500 times since 2006, when the Nationals began holding races among 10-foot-tall foam renderings of Roosevelt, George Washington, Thomas Jefferson and Abraham Lincoln at home games.
The Nationals' very next batter, Zimmerman, led off the bottom of the fourth with his 25th homer, his team's first scoring off Cliff Lee (6-9).
The hitter after that, Michael Morse, doubled and eventually scored, too. In the eighth, Morse added his 18th homer, a two-run shot off reliever Jonathan Papelbon that drew a curtain call.
Lee, who finished with a losing record for the first time since 2007, departed after the sixth. He allowed eight hits and three runs, didn't walk a batter and struck out seven.
In the eighth, Papelbon lost control of a breaking pitch that buzzed near Zimmerman's head, drawing boos from the stands. Papelbon wound up walking Zimmerman, who tipped his cap in reaction to loud cheers as he walked to the dugout, replaced on first base by pinch-runner Bryce Harper. Morse followed with a drive to right-center.
The 19-year-old Harper and first baseman Adam LaRoche were out of the starting lineup - a chance to get a breather before the grind of the postseason begins.
NOTES: By virtue of the NL's victory in the All-Star game, the league's representative gets home-field advantage against the AL in the World Series. ... The season's total attendance of 2,370,794 - an average of 30,010 - was nearly 50,000 higher than the previous high at Nationals Park, in 2008, the first season at the new ballpark. ... After originally planning to sell standing room only tickets on the day of NL division series games, the Nationals announced they would begin making those available Wednesday. ... Washington's second batter of the afternoon, Mark DeRosa, was robbed of a homer by left fielder Juan Pierre, who leaped to make the catch right at the top of the wall. DeRosa was getting a second consecutive start, this time in right field after playing shortstop Tuesday. ... Philadelphia 1B Darin Ruf delivered a sac fly in the fourth. He has driven in all eight Phillies runs in their last four games against Washington. ... He has Phillies CF Nate Schierholtz went 3 for 3, including two doubles. ... Phillies RHP Tyson Brummett made his major league debut in the eighth, allowing two singles and striking out batters.