Mike Magee had a goal and an assist to help the home side take a point off visiting Philadelphia.
Magee got on the board in the 16th minute, sliding in to tap home a cross from Quincy Amarikwa and give his side an early lead.
Maurice Edu pulled the Union level in the 32nd minute, firing home a left-footed effort after a blocked shot fell kindly to him in the penalty area.
Leonardo Fernandes put Philly in front in the 39th when his free kick from near the right touchline drifted past every waiting body in the box and bounced into the far corner of the goal.
Juan Luis Anangono scored the equalizer in the 86th, banging home a free kick from Magee to give the home side a share of the spoils.
Chicago earned a stoppage-time penalty kick when Aaron Wheeler took down Anangono, but Magee saw his penalty kick and rebound attempt stopped by Zac MacMath on the final play of the game.