The 20-year old Homegrown Player product has already travelled to Holland ahead of a two-week stint with the central-eastern club which gave new Crew head coach Gregg Berhalter his professional start back in 1994.
Berhalter said of Trapp: "Wil was anxious to continue his development as a player. He's not a guy that's happy standing still and being stagnant, and he wanted this experience to train abroad and keep improving.
"A natural fit for him is Holland. It's a league with a lot of young players that is known for development, and in Zwolle we are sending him to a club that has clear-cut style of play, tradition and a track-record for developing quality players."
Zwolle, managed by former striker Ron Jans, currently sits ninth on the Eredivisie table after 16 league matches.
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