John Horner came to California in 1846 on the "Brooklyn."
He settled in Mission San Jose and purchased large tracks of land in the area and started farming. He did fairly well growing potatoes, but he was having a problem getting his goods to market in San Francisco.
In 1850, John Horner purchased land around a landing on Alameda Creek. In 1851, he purchased the small steamship, "Union," and set it up to run from his landing in Alvarado to San Francisco. His primary goal was to get his produce to market, but he also used the steamship for passenger traffic.
He also set up a small town around the landing and called it "Union City."
The problem was that no one wanted to go from San Francisco to Union City. The heart of East Bay was still Mission San Jose. So, Horner needed to set up a stage from Union City to Mission San Jose. Since there was no roads, Horner had to create his own road from Union City to Mission San Jose.
In 1852, his roads were finished, so he established his stage from the wharf in Union City to Mission San Jose.
This Jan. 25, 1855 advertisement from the Daily Alta California newspaper, is for the Horner's steamship and stage line:
FOR UNION CITY:
Connecting with stages to Alvarado, Centreville and San Jose Mission.
The Steamer Union, Capt. Charles Thorn, will leave Broadway Wharf every Tuesday, Thursday and Saturday, returning will Union City on Mondays, Wednesdays and Fridays. For freight and passage, which will be at the lowest rates, apply on board at Broadway Wharf.
Another newspaper report talks about a brawl between a driver for the Horner stage and another stage driver in August, 1857:
A difficulty took place on July 28th, between Cameron Duncan, of the Union City line of stages, and Lewis J. Hilt, driver on McLaughlin’s mail line, in which the latter struck the former with a slung shot, and was himself stabbed by the former in the shoulder and right breast, though not seriously injured.
Eventually, Horner built a total of 16 miles of roads and ran stages from Union City to Mission San Jose, and then to the city of San Jose.