The finish line is only a mile away, and the course is mostly downhill. So how fast can you run the Millennium Mile in Londonderry?

That's the question for runners of all abilities as they step to the starting line tomorrow afternoon. More than 600 participants are expected for the annual dash from Londonderry High School past Mack's Apples. Unseasonably warm temperatures (mid-50s) are in the forecast for the 10th annual Millennium Mile set for 2 p.m.

On-line registration ($10 adults, $5 children) continues today through 3 p.m. Race-day registration will be held from noon to 1:45 p.m.

Twenty runners have broken the 4-minute barrier since the inaugural event on Dec. 31, 1999. Others continue chasing a 5-minute mile, 6-minute mile, or whatever carrot is ahead of the rabbit.

"It's funny to hear people talking about this race because it's a distance a lot of people don't normally run, and they don't know what a good time might be," race co-founder John Mortimer, a Londonderry High graduate, said. "The course is mostly downhill, so how fast do you think you should be? It's interesting to hear different mindsets going into this race."

Sprinting specialists may want to consider the "Dash for Cash" bonuses at the quarter-mile ($50), half-mile ($75) and three-quarter-mile ($100) points. An additional $500 will be awarded to anyone breaking the course record.

"Last year, a high school kid went out really hard and got 50 bucks out of it," Mortimer said. "The only stipulation is you have to finish the race. You can go really hard (for cash), then walk if you want."

Awards and cash prizes will be given to the top three overall male and female finishers. Age group winners will receive Reebok merchandise.

Mortimer, a University of Kentucky running coach, won't be able to attend this year's race because his wife, Jennifer (Kramer), is expecting the birth of their first child, John William Mortimer, IV. Both Mortimer and his wife are past Millennium Mile champions.

Scott Anderson of Washington, D.C, set the men's course record of 3 minutes, 51 seconds in 1999. Kansas native Amy Mortimer (no relation to John) set the women's record of 4:20 in 2005.

The Millennium Mile through the years has drawn several elite runners -- and friends of Mortimer and co-founder Matt Downin of Hampstead -- including 2004 Olympic marathon medalist Deena Kastor and U.S. 10K national champion Katie McGregor.

Proceeds benefit the Jack & June Mortimer Memorial Scholarship, which helps defray college tuition for a graduating high school student-athlete.