Lakeside was home to the Kumeyaay prior to European contact, who called Lindo Lake "Ha Ptur" or Ha Pchurr (Barona Tribal dictionary), meaning lake or "circular water".

In 1904, John H. Gay bought the Lakeside Hotel and fenced off the park surrounding Lindo Lake, claiming both as part of his estate.

He then proceeded to construct an automobile and horse racetrack around the lake, which became famous when Barney Oldfield set a new land speed record when visiting for the track's opening in 1907.

[6] The inn and racetrack became a popular gathering place for millionaires and celebrities and consistently drew large crowds by train to watch the races held there, but both were demolished per Gay's wishes at his death in 1920.

The venue is manned and maintained by the El Capitan Stadium Association, an all-volunteer group who aims to assist and support the youth of Lakeside by donating all proceeds from facility rentals to local sports and service, as well as education grants.

During the middle of the 20th century, Lakeside was home to significant Native American, Spanish-speaking and Filipino populations.

Many social and service groups are very active in Lakeside including Youth Venture Teen Centers, VFW, Kiwanis International, Elks, Optimist, Soroptimist, 4-H, FFA, Boys and Girls Club, Boy Scouts, Girl Scouts, United States Naval Sea Cadet Corps, youth soccer, baseball and football leagues, and the Cactus Park BMX track.

Today, protection of the town's history falls to the Lakeside Historical Society, which works primarily to retain and preserve the buildings in the historic former downtown along Maine Avenue, now removed from the central business hub.

Also located in Lakeside is the trailhead for the climb to the summit of El Cajon Mountain, nicknamed locally as "El Capitan" for its resemblance to the famous Yosemite cliff, which dominates the view of the mountains northeast of Lakeside.

According to the United States Census Bureau, Lakeside has a total area of 7.3 square miles (19 km2).

[11] As of the census[14] of 2000, there were 19,560 people, 6,849 households, and 5,150 families residing in the census-designated place (CDP).

There were 7,776 housing units at an average density of 1,068.0 per square mile (412.4/km2), of which 5,066 (69.0%) were owner-occupied, and 2,281 (31.0%) were occupied by renters.