The Thorns (1-0-1) got the first win in franchise history and drew 16,479 to Jeld-Wen Field a record for the National Women's Soccer League in its debut season.
Portland dominated throughout, outshooting Seattle 12-5.
The Thorns have two Olympic star forwards in Morgan and Canada's Christine Sinclair. That duo teamed up on the second goal 7 minutes into the second half.
Seattle (0-1-1) was without most of its marquee players. Goalie Hope Solo is out until late summer with a wrist injury, while midfielder Megan Rapinoe is currently playing in France and won't be available to the Reign until June.
The Thorns' home-opening crowd was more than double the NWSL's previous high of 6,784. Through six league matches, the average attendance is 5,737 per game.
Among those in attendance were the Rose City Riveters, the women's fan counter to the Major League Soccer's Timbers Army. The red-and-white clad Riveters aren't quite as large or loud as the Army, but prominent nonetheless. The Riveters had a large banner below their sections that says "City of Thorns," a play on the Portland's moniker of City of Roses.
At times, the Riveters turned their wrath at Seattle's Jessica Fishlock. The midfielder from Wales pounded her chest after scoring a goal during the 74th minute, then later mockingly waved to the Riveters after drawing a yellow card.
Portland had several scoring chances during the first half, and finally broke through seconds before halftime on a set play. Nikki Washington lobbed a ball into the penalty box to Dougherty, whose 10-yard header landed into the left corner of the goal.
Perhaps the game's loudest cheer came during the 52nd minute, when Sinclair passed to a wide-open Morgan, who then finished with an eight-yard shot to the right corner to give the Thorns a 2-0 lead.
Portland became the first NWSL team to score at least two goals in a game. The combined three goals were the most scored in a NWSL game this season.