Cal. Gov. Code § 23119
The boundaries of Los Angeles County are as follows:
Beginning at a point in the southwesterly boundary line of the State of California, said point being on the southerly prolongation of the westerly boundary line of Rancho Topanga Malibu Sequit; thence northerly along said prolongation and westerly line of said rancho to the northwesterly corner thereof; thence northeasterly in a direct line to corner number seven of the boundary of Rancho Simi; thence easterly along line number seven, northerly along line number eight, easterly along line number nine of the boundary of Rancho Simi to corner number ten of the boundary of Rancho Simi; thence following the boundary line as surveyed by E. T. Wright and J. T. Stow, county surveyors, in June and July, 1881 as shown on map recorded in book 43, page 25 et seq., miscellaneous records of Los Angeles County as follows: north 105.01 chains to a point; thence north 07 degrees 29 minutes W., 157.50 chains to a point; thence north 21 degrees 57 minutes W., to a point in the north line of Sec. 4, T. 8 N., R. 19 W., S. B. B. & M., distant westerly along said north line 1,400 feet, more or less, from the northeast corner of said Sec. 4, said point being common to the boundaries of Kern, Ventura, and Los Angeles; thence east along the north line of T. 8 N., S. B. B. & M., to the easterly line of Golden State Freeway (Interstate 5); thence southwesterly, southerly, and southeasterly along said easterly line to the south line of Sec. 3, T. 8 N., R. 19 W., S. B. B. & M.; thence easterly along said south line and the south line of Sec. 2, T. 8 N., R. 19 W., S. B. B. & M., to the southeast corner of said Sec. 2; thence northerly along the east line of said Sec. 2 to the north line of T. 8 N., S. B. B. & M.; thence easterly along the north line of T. 8 N., S. B. B. & M. to the northeast corner of T. 8 N., R. 8 W., S. B. B. & M., said corner being a point common to the boundaries of San Bernardino, Kern, and Los Angeles;
Thence south along the range line between R. 7 and 8 W., to the southeast corner of T. 6 N., R. 8 W., S. B. B. & M.; thence east along the township line between T. 5 and 6 N., to the northeast corner of T. 5 N., R. 8 W., S. B. B. & M.; thence south along the range line between R. 7 and 8 W., to a point in the east line of Sec. 12, T. 4 N., R. 8 W., S. B. B. & M., distant southerly 940 feet, measured along said east line, from the northeast corner of said Sec. 12; thence southerly in a direct line to the summit of San Antonio Peak; thence southerly along a straight line which passes through the northwest corner of Rancho Cucamonga to a point in said straight line distant south 11°51'04" west thereon, 333.81 feet from its intersection with the north line of Tract 37, T. 2 N., R. 7 W., S. B. B. & M.; thence north 25°38'59" west, 15.06 feet; thence south 70°15'29" west, 47.76 feet; thence south 09°57'30" east, 62.51 feet; thence south 34°17'02" east, 36.94 feet to said straight line; thence continuing southerly along said straight line to a point in said straight line distant north 11°51'04" east, 547.37 feet from its intersection with the south line of said Tract 37; thence south 84°57'02" west, 35.25 feet; thence south 23°47'27" west, 75.70 feet to the beginning of a nontangent curve concave to the southwest having a radius of 181.00 feet and to which beginning a radial line bears south 29°24'24" west; thence southeasterly along said curve through a central angle of 12°08'32" an arc distance of 38.36 feet to the beginning of a reverse curve concave to the northeast having a radius of 169.00 feet; thence southeasterly 16.07 feet along said curve through a central angle of 05°26'52" to said straight line; thence southwest in a direct line to the northwest corner of Rancho Cucamonga, thence southwesterly along the northwesterly boundary line of Rancho Cucamonga to the most westerly corner of Rancho Cucamonga; thence southwesterly in a direct line to the northeast corner of Rancho San Jose; thence southwesterly and westerly along the easterly and southerly boundary lines of Rancho San Jose to the range line between R. 8 and 9 W. in T. 2 S., S. B. B. & M.;
Thence south along the range line between R. 8 and 9 W., to the southeast corner of Sec. 12, T. 2 S., R. 9 W., S. B. B. & M., said corner being an angle point in the boundary line of Rancho Santa Ana del Chino; thence westerly, southwesterly, southerly, easterly, and southerly along the boundary line of Rancho Santa Ana del Chino to the southwest corner of Rancho Santa Ana del Chino, said corner being the center of Sec. 35, T. 2 S., R. 9 W., S. B. B. & M.; thence southeasterly in a straight line to a point in the south line of Sec. 36, T. 2 S., R. 9 W., S. B. B. & M., distant 52.84 feet easterly thereon from the southwest corner of said Sec. 36, said point being common to the boundaries of San Bernardino, Orange, and Los Angeles; thence westerly along the northern line of Orange to the southeasterly corner of Tract No. 46685 filed in Book 1209, pages 56 and 57, of Maps, in the office of the Recorder of the County of Los Angeles, said southeasterly corner being common to the boundaries of Orange and Los Angeles; thence northerly following along the boundary of said Tract No. 46685, the following courses: north 13°53'07" east 100.12 feet, north 76°01'25" west 1018.58 feet, north 85°34'56" west 163.25 feet, and south 00°57'29" west 47.01 feet to a point in the northerly line of Tract No. 25335, filed in Book 775, pages 35 and 36, of said Maps, said point distant westerly along said northerly line 10.26 feet from the northeasterly corner of said Tract No. 25335; thence northwesterly following along the boundary of said Tract No. 25335 the following courses: north 76°00'59" west 1224.52 feet and south 00°52'39" west 564.75 feet to a point on the boundary common to Orange and Los Angeles; thence westerly along the northern line of Orange to the southwesterly boundary line of the State of California; thence northwesterly along the southwesterly boundary line of the State of California to the point of beginning. Also the Islands of Santa Catalina and San Clemente.
Ca. Gov. Code § 23119