Knightsen is a census-designated place (CDP) in Contra Costa County, California, in the United States.

[6] The community worries about urban sprawl from expanding development in neighboring Oakley.

[6] However, a significant portion of the community lies within the agricultural conservation zone in the Brentwood, California, general plan.

[7] During the 1880s, settlers began moving in and planting the first almond trees in the area.

Until the railroad was built, farmers shipped their produce via water, using Babbes Landing off Dutch Slough, near the north end of what is now Sellers Avenue.

[8] Knightsen was founded in 1898, when the Atchison Topeka and Santa Fe Railroad (Santa Fe Railway) was planning to lay a track through the area to reach Stockton, California.

According to local historian, Kathy Leighton, the railroad wanted to name the community Meganos, commemorating the nearby ranch owned by Doctor John Marsh.

He immediately constructed the first retail store in Knightsen, a grocery, in which he could also locate the post office, which opened in 1900.

[8] Voters approved forming the Knightsen Irrigation District in 1920 to provide water to 10,000 acres (40,000,000 m2) of farmland.

It built a hall in 1922 that has since been used for school graduations, dances, weddings, political functions, school plays, holiday celebrations, church services, a safe haven for flood victims and an endless list of other events.

Knightsen has remained primarily a farming community, growing such foods as almonds, walnuts, sunflower seeds, etc.

[6] According to the United States Census Bureau, the CDP has a total area of 8.5 square miles (22 km2), 99% of it land.

100 households (18.8%) were made up of individuals, and 31 (5.8%) had someone living alone who was 65 years of age or older.

17.1% of all households were made up of individuals, and 8.9% had someone living alone who was 65 years of age or older.