The Terrapins controlled much of the play during the first half at Artificial Turf Field, outshooting the Tar Heels 9-4. In the second half, Maryland got off three shots to UNC's two.
UNC won the pushback when overtime began and carried the ball downfield untouched by Maryland to set up McCann's goal just 30 seconds into the period. McCann dived to tip in a cross from junior back Abby Martin for the winning goal.
"We were fortunate to get to overtime," UNC coach Karen Shelton said. "We didn't play very well in the first half - Maryland dominated - but our kids played better in the second half to force the overtime. I'm delighted with the win, and I'm proud of our team."
The game was the third consecutive shutout for the Tar Heels and goalkeeper Amy Tran, who made six saves against Maryland.
With the victory, UNC finished ACC play with a record of 4-0 to claim the regular-season championship.
The Tar Heels, who earned the top seed in the ACC tournament, are now 16-1. The Terrapins are 14-3 (2-2).
Barksdale Picked Preseason All-ACC
GREENSBORO - North Carolina forward LaQuanda Barksdale was tapped as a 2000-2001 preseason All-ACC player at the ACC Women's Basketball Media Day on Sunday.
Barksdale, a senior from Winston-Salem, led the league last season with 17.6 points per game and 8.6 rebounds per game and was named to the All-ACC team.