The tartan is based on the Muir Clan tartan to honor the great naturalist John Muir. However, it is original enough to be registered with the Scottish Tartan Authority as California State District Tartan Number 200111 and with the Scottish Tartans Society as Tartan 2454.

The official State Tartan is described as a pattern or sett consisting of alternate squares of meadow green and pacific blue that are separated and surrounded by narrow charcoal bands. The squares of meadow green are divided by a gold seam that is supported by charcoal lines on each side. There are three redwood stripes, the middle of which is broader, that are added to each side of the gold seam. The pacific blue square is divided by a sky blue stripe, which is supported on each side by charcoal lines.

The tartan's blue reflects the sky, the ocean, and the state' s rivers and lakes, while the green stands for the state's mountains, fields, and parks. The red, gold, and blue seams signify the arts, sciences, agriculture, and industry of California.