John S. Hager (March 12, 1818-March 19, 1890) was an American politican from the U.S. state of California. He served in the U.S. Senate from 1873 to 1875. Hager was born near Morristown, New Jersey, on March 12, 1818. He completed preparatory studies and graduated from the College of New Jersey (later named Princeton University) in 1836. Hager studied law and was admitted to the bar in 1840, practicing in Morristown.
In 1849, Hager moved to California and engaged in mining during the California Gold Rush.He practiced law in San Francisco and was a member of the state constitutional convention in 1849. Hager served in the California Senate from 1852 to 1854, before being elected as a state district judge for the district of San Francisco in 1855. Hagar remained a district judge until 1861. In 1865, Hagar returned to the state senate, serving until 1871, when he was elected a regent of the University of California
Hagar was elected as a Democrat to the U.S. Senate to fill the vacancy caused by the resignation of Eugene Casserly and served from December 23, 1873, to March 3, 1875. He was not a candidate for renomination in 1874.
In 1879, Hagar was a member of the state constitutional convention. He was collector of customs of the port of San Francisco from 1885 to 1889. Hagar died in San Francisco on March 19, 1890 and was interred at Bellefontaine Cemetery in St. Louis, Missouri.
This article incorporates facts obtained from the public domain Biographical Directory of the United States Congress.
Preceded by: Eugene Casserly U.S. Senator (Class 1) from California 1873-1875 Succeeded by: Newton Booth