Jackson's time of 18:03.91 topped the previous record of 18:18 held by Hereford's Kristen Malloy.
Jackson held off Hereford senior Kelly Wesolowski (18:28.95) and Middletown's Reilly Caldwell (18:43.69) for the title.
"I was not surprised that the course record fell today," Dulaney coach Chad Boyle said. "Haley, Reilly and Kelly, with those three together providing that level of competition, I knew someone was going to break the record."
Jackson primed for the race by sleeping in the car on the way up from Calvert County.
During the prerace walkthrough she let her teammates wake her up.
"Before races we are just joking around during the course walk, listening to music together, like John Cena and SpongeBob songs, and having our inside jokes," Jackson said. "It makes it so much easier to calm down and enjoy the race even more."
Second-place finisher Wesolowski made her antsy during the race.
"Seeing her that close, I got really excited and I was like, 'This is going to be a good year if she's that close.' " Jackson said.
Wesolowski was just happy to be on any course.
She played soccer her freshman and sophomore years and planned to switch to cross country for her junior year, but she had foot surgery.
"We are building quite a legacy here," Boyle said. "It's a seamless transition."
Matt Owens (7th, 16:12.70) was the leader of the Dulaney pack.
'There is pressure," Owens said. "We've got to keep up the tradition, but they taught us really well and we've got great coaches and the team is filled with guys with great potential and we are all dedicated."
"Matt Owens stepped up and did a tremendous job," Boyle said. "We call it talking with his legs."
The rest of the top five for the Lions included Brian McCullough (12th, 16:44.89), Brendan O'Brien (20th, 16:52.26), Alex Ozbolt (22nd, 16:55.13) and Connor Martin (25th, 16:56.37).