Adrian Webster blankets George Best and a stout Sounders defense frustrates the high-scoring Los Angeles Aztecs during a 3-1 playoff triumph at the Coliseum. The visitors go in front in the 63rd minute following a remarkable effort by Steve Buttle. After winning the ball, Buttle the ball, makes two dissecting passes on the counterattack and heads in Jimmy McAlister’s cross. Less than four minutes later Micky Cave finishes a cross from Jimmy Robertson, who had scored the opener. The Aztecs entered the match with an NASL-best 65 goals. More than 500 fans greet the team on its arrival the next morning at SeaTac Airport.

The original 1974 NASL Sounders team becomes the first inductee to the club’s newly established Eternal Circle of Legends. The pregame ceremony is part of the club celebrating 50 years of professional soccer in Seattle. Players — eight who are still living — and families from the team are presented with black jackets to commemorate the honor. There are about 120 alumni players representing every previous team on the field as part of the festivities. WA Legends curates an exhibit detailing the inaugural team’s profound impact, both on the field and in the community.

A fan favorite since becoming the starting goalkeeper three years earlier, Tony Chursky is traded by the Seattle Sounders to the California Surf in exchange for U.S. National Team star midfielder Al Trost and the rights to Ray Evans. Chursky is also the team's union representative. In another move in a roster rebuild, John Ryan and Frank Barton come in from Norwich City and Bournemouth, respectively, and John Impey and Jimmy Neighbour arrive on loan. They join newcomer Alan Hudson and the return of veteran goalkeeper Mike Ivanow.

Walla Walla becomes the second collegiate four-year program to finish winless in back-to-back seasons, losing to Carroll College, 4-0, in Helena, Mt. the Wolves (0-13-0), who were 0-15-0 in 2015, did not manage to score a single goal and allowed 10 or more in four games. Their losing streak has reached 32 games, dating back to 2014.

An extra-time strike from the red-hot Osaze De Rosario sends the Tacoma Defiance past the Oakland Roots of the USL Championship, 2-1, in a third-round U.S. Open Cup match at Starfire. Tacoma is the last remaining MLS Next Pro team remaining in the round of 32. In the 108th minute, De Rosario delivers the upset of the Div. 2 Roots with his fifth goal in the first seven games across all competitions. He scores four times in his next four games to earn a Sounders first-team contract on May 8.

Leaders from five districts – Seattle, East Side, Tacoma, Federal Way and Snohomish – unite to form the Washington Junior Soccer Association. Mike Ryan is elected president, adding to his existing duties as coach of Washington varsity, Buchan Juniors and vice-president of senior state association. Ryan had begun recruiting associations for a meeting at his Lake City home in October.