Video Observer: O’Neill Regional Park is Historically Connected to Fullerton

By Emerson Little on November 10, 2025

Entrance to O’Neill Regional Park

Nestled in the canyons of South Orange County is O’Neill Regional Park, a surprisingly remote 4,000 acres of protected wilderness that happens to be open for both equestrian and group camping (campsite registration required). While certain areas of the regional park closely resemble portions of Coyote Hills, this area of Orange County is historically linked to Fullerton in a couple of ways.

Entrance to Pawfoot Trail in O’Neill Regional Park

Back in the summer of 1769, Spanish conquistador Gaspar de Portola led an expedition team into what’s now present-day Orange County. According to local historian Jesse LaTour’s “Fullerton History: A hyperlocal exploration,” Portola was accompanied by soldiers and Franciscan missionaries on this first Spanish overland expedition through California.

LaTour writes, “The impetus for the expedition was concern by the Spanish crown that English and Russian explorers would encroach on ‘their’ territory (Alta, or upper, California)…The Portola expedition was the first attempt at actual colonization, not just exploration.”

Heading inland on July 24, 1769, Portola and his soldiers camped on the western edge of a large plateau located on the eastern side of Trabuco Creek (three miles downstream from present Trabuco Oaks), according to OC Parks’ history webpage for O’Neill Regional Park. Trabuco Creek still runs through the park today. One of the men on the expedition lost his musket (in Spanish, his trabuco) here while camping.

Panoramic view from Mesa Trail at O’Neill Regional Park

The County writes, “to mark this loss, the stream was named Trabuco,” a title which soon became associated with the surrounding area. Portola’s 1769 expedition eventually took the soldiers further north, and by July 29, they reached the Fullerton area, according to historian Bob Ziebell in his book “Fullerton: A Pictorial History.” C.E. and Marilyn Parker wrote in “Orange County: From Indians to Industry” about how the Spanish expedition camped slightly west of Harbor and a short distance below Brea Dam before continuing northwest.

The route that Portola’s soldiers followed later became known as the El Camino Real (aka “The King’s Highway”), which is currently marked by a bell monument in Fullerton’s Harbor Boulevard median between Wilshire and Amerige.

The land O’Neill Park now sits on was once a part of the old Rancho Trabuco, which was first granted to a man named Santiago Arguello in 1841, when California was still a province of Mexico, by Governor Alvarado, according to OC Parks. Many pioneers of Orange County owned the ranch before it was acquired and subsumed into the much larger O’Neill Ranch.

Entrance to Edna Spaulding Trail in O’Neill Regional Park

OC Parks writes in the park brochure that, in 1948, the O’Neills donated 278 acres of Trabuco Canyon to Orange County to establish the County’s second regional park. An additional 278 acres were donated in 1963. More land purchases and donations were made over the years, including more than 400 acres in 2011 by Rancho Mission Viejo, all of which have expanded the park’s boundaries to nearly 4,000 acres.
Since O’Neill Park happens to be one of the oldest parks in the county system, there’s another historical Fullerton connection here as well. According to OC Historyland, a fascinating website written by Orange County historian Phil Brigandi, one of the many scenic nature trails in O’Neill Park is named after longtime FUHS instructor Edna Spaulding. This is the Edna Spaulding Nature Trail. She was an expert on local wildflowers and taught science at Fullerton High School from 1923 to 1951.

According to Brigandi, Spaulding started using the east side of the park for school field trips in the early 1950s. Then, in the mid-Sixties, at the suggestion of the Audubon Society, an old roadway through a side canyon was converted into a self-guided nature trail and named in honor of Spaulding.
Today, this remote 1-mile loop trail is walkable in O’Neill Regional Park. It takes hikers, equestrians, bike riders and outdoor enthusiasts through a coastal sage scrub canyon providing excellent views of the surrounding land.

With more than 9,000 inventoried trees, O’Neill Regional Park is roughly an hour drive away from Fullerton. My dad and I drove down Chapman Avenue in Orange until it turned into Santiago Canyon Road and then made a left by Cook’s Corner onto Live Oak Canyon Road. This scenic drive led us straight to the park’s entrance.

The park was originally dedicated on June 18, 1950, and a memorial to the park’s namesake, Richard O’Neill, now sits in the divider between the park entrance and exit. Two friendly park rangers greeted us as we pulled up to the toll station at the park entrance.

view from Edna Spaulding Trail

It costs us $3 for our vehicle to get into the park on a weekday, but it’s worth mentioning that park admission is $5 on the weekend. The park’s interpretive center is also open on weekends and ranger tours are offered.

On the front page of the pamphlet the ranger handed me, I read in big capital letters that we were entering mountain lion country, a wilderness area where mountain lions may be present and unpredictable. There were many signs throughout the park that reinforced this idea of proceeding with caution, especially since mountain lions have been known to attack without warning.
According to the OC Parks handout, “your safety cannot be guaranteed. You are advised to stay alert for potential danger.”

I had read ahead about this on the park’s website, which is why my dad and I brought hiking sticks with us, just in case we encountered any wild animals while we were out hiking.

While we didn’t encounter any mountain lions during our time at the park, it is important to know what to do if you encounter them: don’t run, don’t crouch, stand your ground and wave your hands, shout, and be as loud as possible. I learned that you need to do everything you can to make yourself appear larger and convince the lion that you are not prey, so that it thinks you’re dangerous.

view from scenic overlook at O’Neill Regional Park

The best hike I went on with my dad in O’Neill Park was the Mesa Trail, which provides a grand panoramic view of the surrounding wilderness from an elevated height. I’d arrived on the Mesa Trail early on an overcast October morning and spotted low-hanging clouds sitting on top of the surrounding mountains.

This hike is also part of the Storywalk Project, created by Anne Ferguson of Montpelier, VT, and developed in collaboration with the Kellogg-Hubbard Library, with 20 signposts featuring illustrations telling the hero’s journey of a bear as it navigates different seasons.

I saw many parents with younger children enjoying this story. From the Mesa Trail, you can also look down at some of the individual camp sites. I would recommend bringing binoculars for bird watching and hiking up to Vista Point, which is situated at an elevation of 1,492 feet at the peak of the park and offers stunning 360-degree views of Orange County. According to the ranger, on a clear day, you can even see as far as Catalina and Palos Verdes.

Starting November 2, fall-winter hours begin at O’Neill Park and many other regional parks across Orange County. Fall-winter hours are 7 am to 6 pm. Trails may be closed up to three days following rain. O’Neill Regional Park is located at 30892 Trabuco Canyon Road. For further information, visit https://www.ocparks.com/oneill.