California Junction is an unincorporated community and census-designated place (CDP) in Harrison County, Iowa, United States.

The community is 1 mile (1.6 km) northeast of the Iowa–Nebraska border, which in this area follows the center of De Soto Lake, an abandoned channel of the Missouri River.

According to the United States Census Bureau, California Junction has a total area of 0.461 square miles (1.19 km2), all of it land.

[7] Yazoo Landing was a ferry crossing on the Missouri River where the Blair Bridge now stands.

John I. Blair, the railroad tycoon, believed that this would be an important hub for passengers heading west, and gave the town its current name.

[13] By 1915, there was also a town hall, high school, general store, blacksmith shop, post office, two churches, and a train station.

[7][13] On January 1, 1922, a 1460-foot deep well was drilled at the nearby oil prospect of Hugh R. Coulthard,[14][15] a prominent landowner, businessman, and farmer from California Junction.