The course hasn’t changed much since 1973, but the Honolulu Marathon’s route still offers room for growth.

While the 26.2-mile trek through East Honolulu remains the centerpiece, the marathon’s reach has expanded into a full weekend featuring three events.

The Kalakaua Merrie Mile kicks off the weekend Saturday morning, with Sunday’s marathon accompanied by the Start-to-Park 10K.

Honolulu Marathon president Jim Barahal noted the marathon course covers 10 kilometers from the starting line on Ala Moana Boulevard to the finish at Kapiolani Park, thus offering an alternative to the 26-mile commitment.

Both Sunday races start with the 5 a.m. fireworks show, so 10K participants “get the marathon experience,” Barahal said.

The Start-to-Park 10K — rebranded from the race day walk — is part of the marathon’s “Honolulu 2020” initiative targeting 40,000 combined participants in the various events in the next three years.

Barahal projects the Kalakaua Merrie Mile to draw close to 1,800 entrants and the Start-to-Park 10K will be capped at 4,400. Entries for Sunday’s marathon are expected to reach 28,000.

Barahal is hopeful cool and dry conditions carry over to Sunday, when runners will be led onto the course by a pack of elite runners that includes world-record holder Dennis Kimetto and defending champion Lawrence Cherono, who broke the race record last year.

Kimetto set the marathon world record of 2 hours, 2 minutes, 57 seconds at the Berlin Marathon in 2014. Last year, Cherono and runner-up Wilson Chebet finished under the previous Honolulu record of 2:11:12, with Cherono crossing the finish line in 2:09:38 and Chebet following at 2:10:49.

Women’s champion Brigid Kosgei also returns, along with two-time winner Joyce Chepkirui.

Among the throng aiming for personal goals will be Olympic figure skater Mao Asada, who won three world championships and a silver medal at the 2010 Games in Vancouver for Japan.

Saturday’s Merrie Mile features Edward Cheserek, a 17-time NCAA champion at Oregon in cross country and indoor and outdoor track and field, and two-time Olympic 1,500-meter medalist Nick Willis of New Zealand.

Barahal said he was “blown away” by the response for last year’s Merrie Mile — the eighth-ranked road mile in the U.S. — and is aiming to reach No. 2 in coming years.

The Honolulu Marathon Expo opens Thursday at the Hawaii Convention Center and runs through Saturday. Registered runners must pick up their race packets at the expo. Late entries are accepted until 5 p.m. Saturday.

Traffic advisory

Traffic closures along the marathon route will start Sunday at 12:30 a.m. Areas of downtown, Kakaako, Ala Moana, Waikiki, Diamond Head, Kahala and east Honolulu will be affected. There will be lane closures, tow-away zones and rerouting of TheBus.

The route runs to Kakaako, downtown and continues through Ala Moana, Waikiki, Diamond Head, Kahala and into East Honolulu. Runners turn around in Hawaii Kai and head back to the finish line at Kapiolani Park.

Traffic questions can be directed to info@honolulumarathon.org or 808ne.ws/2B111Tu.