One of the state’s largest long-distance running events has a new name and now will include the heart of the city and Kansas University as its course.

The new Lawrence 1/2 Marathon and 5K will be April 15 – a Sunday morning – and organizers hope the event, formerly known as the Raintree Run, still can pull in the more than 1,600 runners who participated in last year’s race in southwest Lawrence.

“This thing has potential to just go way past that, but it’s hard to tell in the first year,” said Steve Riley, of Lawrence, who is organizing the run with his wife, Marcia.

The popular Raintree Run helped pay for scholarships and improvements at Raintree Montessori School for about a decade. But Raintree’s owners, Keith and Lleanna McReynolds, said the school would be unable to play host to the race because the couple’s grandson, Gibson Huston, a Raintree student, recently had brain surgery, Marcia Riley said. And they wanted to give the race to the Lawrence community.

Steve Riley and other running enthusiasts had a vision for a new 13.1-mile course that began at Haskell Indian Nations University and included Massachusetts Street, most of East Lawrence, Old West Lawrence and Jayhawk Boulevard.

The organizers also found a new beneficiary for the half-marathon and 5K run in the Health Care Access Clinic, 1920 Moodie Road, a nonprofit clinic that offers and facilitates medical services for residents without health insurance. The clinic recently had $38,000 cut from its budget, Marcia Riley said.

Funds raised through a 1-mile Fun Run and Walk will help pay expenses of Gibson Huston’s brain surgery, Marcia Riley said.

While the event is a few months away and still a work in progress, organizers have one early fear.

“One of our biggest problems is competing against ourselves,” Marcia Riley said.

She is afraid some interested runners would see advertisements for the Lawrence 1/2 Marathon and 5K and decide not to register because they would be waiting for the Raintree Run.

But the new run is taking the Raintree Run’s place from now on, and it will include the traditional food fest.

The run will begin just after 8 a.m. at the Coffin Sports Complex at Haskell Indian Nations University. For the half-marathon, the course runs through East Lawrence, Massachusetts Street, Old West Lawrence, and Memorial Drive and Jayhawk Boulevard at KU. Runners will pass by the former homes of Langston Hughes, William S. Burroughs, John Haskell and John Speer and James Naismith’s grave along the way.

The city, Lawrence Police Department, Lawrence Sports Commission, Downtown Lawrence Inc., KU and Haskell all have given support and permission for the new route.

“That time of morning on a Sunday there’s not a lot of traffic,” Steve Riley said.

The half-marathon and 5K run will end in an Olympic Marathon-style finish with a lap around the track at Haskell Stadium.

The organizers are still looking for a headline sponsor and hundreds of volunteers. Interested sponsors have until Dec. 5 to sign up to be included on the event’s entry form. More information is available by calling 842-4351 or sending an e-mail to srmriley@sunflower.com or on the Web site, www.lawrencehalfmarathon.com.

Race registration will likely begin in January, but interested participants can register online now at www.active.com

The new course will be spectator-friendly, the Rileys say, and they would like to see the event take off and become a major boon for Lawrence.

“It could be one of those destination events where people come specifically to Lawrence for something just like this,” Steve Riley said.