California Code, Government Code - GOV § 23125

The boundaries of Modoc County are as follows:

Commencing at the northeast corner of the State of California; thence west, along the northern boundary line of said State, to the range line between R. 4 and 5 E., M.D.B. & M.; thence due south, on said range line, to the southern boundary line of Siskiyou; thence east along an extension of said southern boundary line, to the state line; and thence north to the place of beginning.