The Humboldt meridian in California, longitude 124° 07' 10" west from Greenwich, intersects the base line on the summit of Mount Pierce at latitude 40° 25' 02" north (co-ordinates in NAD27 datum), and governs the surveys in the northwestern corner of California, lying west of the Coast Range of mountains, and north of township 5 south, of the Humboldt meridian system. This principal meridian was established in 1853.
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Humboldt meridian Wikipedia(Text) CC BY-SA