Daniel Gazdag and Nathan Harriel also scored for the Union, who improved to 10-0-5 at home. The Eastern Conference-leading Union, who clinched a playoff berth, are the lone club in Major League Soccer without a home loss.
Gazdag scored his franchise-record 17th goal of the season.
The Union (16-4-9, 57 points) won their third match in a row, outscoring their opponents 16-1 in the process. The 16 goals top the 15 scored by the LA Galaxy in 1998 for the MLS record over a three-game span.
Andrew Gutman recorded the only goal for Atlanta United (8-11-9, 33 points). The club has registered just one road win all season.
Atlanta earned its first corner kick in the 16th minute and the cross went through the box and out of bounds.
The Union quickly turned aggressive and Carranza scored from just outside the top of the box in the 18th minute for a 1-0 lead. It was Carranza's 14th goal of the season.
Atlanta United soon tied the game at 1. Philadelphia goalkeeper Andre Blake made a nifty one-handed save, but Gutman dove in and headed the ball into the net in the 24th minute.
The Union took a 2-1 advantage in the third minute of first-half stoppage time as Uhre connected on a shot through traffic in the box.
Atlanta's Luiz Araujo ripped a shot in the 48th minute, but it landed high and wide. His teammate Thiago Almada had an even better chance in the 58th minute when he broke free in the middle of the box, but he misfired high over the net.
Gazdag scored in the 67th minute to give the Union a 3-1 edge. Cory Burke got the assist.
Harriel notched his first career goal in the fifth minute of second-half stoppage time. The 21-year-old defender was playing in his 27th match for Philadelphia over the past two seasons.