The twice World Cup winner, who helped form OL Reign's identity from its inception and spent the entirety of her 11-season NWSL career with the club, bid farewell at Lumen Field, the home stadium of the NFL's Seattle Seahawks.
"It just feels like home. It was always the safest place," Rapinoe said of her time in Seattle.
"This was just always the place where I could be myself."
Rapinoe's teammates took the field in number 15 warmup shirts in her honour before a video tribute featuring sports icons, including tennis trailblazer Billie Jean King and Seattle baseball great Ken Griffey Jr., played in the stadium.
"I am a little bit at a loss for words," the Olympic champion and 2019 Ballon d'Or winner said in on-field remarks after the match.
"To be able to play here my whole career, in one city... it's just really special to be able to have this."
Rapinoe had already called time on her international career, wearing the US crest for the last time last month in a friendly against South Africa.
Her fourth and final World Cup campaign ended disastrously this year as the Americans suffered their worst-ever performance at the global showcase when they exited in the Round of 16.
The draw on Friday was not what OL Reign had hoped for on a hunt for a place in the playoffs, as Washington goalkeeper Aubrey Kingsbury stopped two fine attempts by Rapinoe in the 50th and 61st minutes.
OL Reign keeper Claudia Dickey leapt up to stop Spirit midfielder Dorian Bailey's shot from outside the box in the 89th minute and made a superb effort to thwart two stoppage-time attempts from Rapinoe's national teammate Trinity Rodman.
Players from each side hugged Rapinoe as she stepped off the field to roars from the crowd, which included her five-time Olympic basketball gold medallist fiance Sue Bird.
"It's been such an incredibly journey," said Rapinoe. "Thank you - to everyone."
