University of North Carolina freshman Lindsay Tarpley's 28th-minute goal answered an earlier strike by Germany's Linda Bresonik, and Wilson followed with tallies in the 30th and 45th minutes as the Americans took control of the match.
The United States will take CONCACAF rival Canada, which advanced to the final on penalty kicks after playing Brazil to a 1-1 tie in the second game of the semifinal doubleheader at Commonwealth Stadium in Edmonton. The games drew a crowd of 37,194, most of whom arrived for the nightcap.
The Americans are 5-0 and have outscored foes, 25-2, but they found themselves behind for the first time in the tournament after Bresonik clinically finished a feed from Anja Mittag in the 16th minute.
The goal was preceded by two shots that hit posts, one by each side. Mittag, set free on the left after a U.S. giveaway, struck high on the near post in the 15th minute, and Tarpley found the right post from a Wilson pass within a minute.
Seconds later, UCLA freshman Jill Oakes' pass to the wing was too casual, and Mittag broke down the right wing. She took the ball to the end line, then cut it back between Oakes and Santa Clara's Jessica Ballweg for Bresonik, who first-timed the ball from 10 yards between goalkeeper Ashlyn Harris, a Florida high-schooler, and the right post.
The United States took charge a dozen minutes later. A German clearance was headed back toward the box from midfield, and Tarpley sent the ball to the left for Heather O'Reilly. The New Jersey high-schooler beat a defender to the left of the goal, then dropped the ball back to Tarpley, who toe-poked it to the upper-near post to tie the score. The goal was U.S. captain Tarpley's fifth of the tournament.
Wilson made it 2-1 less than two minutes later, beating an offside trap to run onto a through ball from Tarpley, left-footing it past Germany goalkeeper Miriam Elling.
Wilson scored her second just before halftime, redirecting a corner kick from University of North Carolina freshman Lori Chalupny.
The second half belonged to the Americans, who owned midfield and continually went forward on quick attacks. Tarpley nearly scored her second in the 56th minute, beating Elling with a header from a chip from Santa Clara's Leslie Osborne, but German defender Alexandra Stegmann dived to head the ball off the goal line.
A retreating Oakes did likewise for the United States in the 63rd minute, flicking a Patrizia Barucha chip off the goal line.
Oakes made it 4-1 in the 86th minute with a brilliant left-footed drive -- after Elling punched away a corner kick -- into the upper-left corner from 22 yards. O'Reilly hit the crossbar four minutes later.
HOST CANADA survived its toughest test of the tournament in a mesmerizing clash, with the University of Washington's Clare Rustad scoring the Canadians' goal and SMU's Erin McLeod coming up big in the nets.
University of Portland All-American Christine Sinclair nearly gave the Canadians the victory in regulation and again in overtime. Her shot deflected off the crossbar in the 86th minute, and Brazilian goalkeeper Giselle stopped her penalty kick five minutes into overtime.
Rustad headed in a Melanie Booth corner kick in first-half stoppage time to give Canada a lead, but Marta scored sixth goal of the tournament when McLeod bobbled her shot from a steep angle over the goal line in the 69th minute.
McLeod made several outstanding saves to counter her error, and Canada captured the semifinal when Sasha Andrews converted her spot kick for a 4-3 triumph in the tiebreaker.
FIFA U-19 WOMEN'S WORLD CHAMPIONSHIP
Aug. 29 at Edmonton
United States 4 Germany 1. Goals: Tarpley 28, Wilson 30, 45, Oakes 86; Bresonik 16.
United States -- Harris; Ballweg (Dowling, 46), Buehler, Oakes, Fletcher; Makoski (Kakadelas, 65), Osborne, Chalupny; O'Reilly, Tarpley, Wilson.
Germany -- Elling; Zietz, Krueger, Guenther, Stegmann; Sabel, Odebrecht (Richter, 82), Bachor (Mueller, 46), Brendel; Bresonik, Mittag (Barucha, 46).
Yellow cards -- Germany: Mittag 43.
Referee -- Krystyna Szokolai (Australia). A -- 37,194.
Canada 1 Brazil 1 (Canada advances on penalty kicks, 4-3). Goals: Rustad 46+; Marta 69.
Canada -- McLeod; Andrews, Gayle, Booth; Moscato (Vermeulen, 39), Rustad, Chapman, Thorlakson (Rowe, 78); Lang, Sinclair, Tinko.
Brazil -- Giselle; Daiane, Ariana, Tatiana, Michele; Daniela, Renata Costa, Renata Diniz; Kelly, Marta, Cristiana.
Yellow cards -- Canada: Rowe 92+; Brazil: Daniela 26, Ariana 96.
Penalty kicks -- Brazil: Marta NG, Kelly NG, Ariana G, Daiane G, Daniela G; Canada: Chapman NG, Sinclair G, Vermeulen G, Lang G, Andrews G.
Referee -- Anri Hanninen (Finland). A -- 37,194.
Sept. 1 in Edmonton
United States vs. Canada, 2 p.m. MDT
Sept. 1 in Edmonton
Brazil vs. Germany, 11 a.m. MDT