San Sevaine Flats is a small area of flatland east of Cucamonga Peak in the

San Gabriel Mountains The San Gabriel Mountains ( es, Sierra de San Gabriel) are a mountain range located in northern Los Angeles County, California, Los Angeles County and western San Bernardino County, California, United States. The mountain range is part of the Tr ...

in San Bernardino County, California. The area is in the Cucamonga Wilderness in the San Bernardino National Forest, 1.24 miles south of

Bonita Falls Bonita Falls are a set of waterfalls in the San Bernardino National Forest, formed by Bonita Creek, that is said to be 370 or 400 feet (113 or 122 meters) in height, but possibly up to 495 feet high because of two undocumented drops in the canyo ...

South Fork Lytle Creek South Fork Lytle Creek is a tributary of Lytle Creek in San Bernardino County, California San Bernardino County (), officially the County of San Bernardino, is a County (United States), county located in the Southern California, southern portio ...

and north of

Rancho Cucamonga, California Rancho Cucamonga ( ) is a city located just south of the foothills of the San Gabriel Mountains and Angeles National Forest in San Bernardino County, California, United States. About east of Downtown Los Angeles, Rancho Cucamonga is the 28th ...

. It has an elevation of 1,690 meters, or 5,545 feet.

History

Before the flat acquired its current name it was the hideout of the outlaw Tom McCauley better known as James or Jim Henry of the

Mason Henry Gang The Mason Henry Gang were bandits operating in Central and Southern California in 1864–1865. As the Civil War was in progress, they were able to pose as Confederate Partisan Rangers, and their original mission was to rid the area of (anti-slave ...

. When the American Civil War ended in April with Lee's surrender at Appomattox the gang with a price on their heads, came under pressure from the Union Army and law enforcement officials in Central California. They moved into pro secessionist Southern California and split up. Henry with part of the gang moved into the eastern

at San Sevaine Flats from which they began rustling, committing robbery and murder as they did. Henry was killed by a posse led by San Bernardino County Sheriff

Benjamin Franklin Mathews Benjamin Franklin Mathews (1819–1888) was elected Sheriff of San Bernardino County, California, on September 14, 1863, and served from October 1863 to October 1865. Mathews was born April 16, 1819, in Chattanooga, Hamilton County, Tennessee. He ...

on September 14, 1865, at San Jacinto Canyon, just over what was then the San Diego County line, in what is now

Riverside County, California Riverside County is a County (United States), county located in the southern California, southern portion of the U.S. state of California. As of the 2020 United States Census, 2020 census, the population was 2,418,185, making it the fourth-most ...

. The flat was named (but misspelled) for Don

Pedro Sainsevain Don Pedro Sainsevain (né Pierre; November 20, 1818 – October 4, 1904) was a French-born Californian vintner, ranchero, and a signer of the Californian Constitution in 1849. He is best known for his role in Californian winemaking, as one o ...

, who with his brother bought part of

Rancho Cucamonga Rancho Cucamonga was a Mexican land grant in present-day San Bernardino County, California, given in 1839 to the dedicated soldier, smuggler and politician Tiburcio Tapia by Mexican governor Juan Bautista Alvarado. The grant formed parts of pr ...

in 1865 and set out a large vineyard. He moved to Cucamonga in 1870 and ran the vineyard and winery with Joseph S. Garcia. In 1874 the Sainsevain brothers purchased land in Hawker Canyon four miles east of Etiwanda and built a large stone house and a reservoir there.

References

San Gabriel Mountains {{SanBernardinoCountyCA-geo-stub