Letter with the Overland Mail from San Francisco to New York 1859

Postal stationary U18 of the USA. Mailed from San Francisco to New York, postmarked in San Francisco on September 5, 1859. No other postmarks present. Handwritten annotation "Per overlandmail via Losangeles" and in pencil "Rec.d Oct 1(?)".

On September 16, 1857, the Postmaster General signed a six-year contract with a consortium (Overland Mail Company), led by John Butterfield as president, for a mail route from St. Louis to San Francisco. This route, No. 12578, ran south, began at St. Louis and at Memphis, joined at Fort Smith, and ran through Fort Belknap, El Paso, Tucson, Fort Yuma, Los Angeles, Fort Tejon, Visalia to San Francisco. The contract went into effect on September 15, 1858. This mail route is also known as the "Butterfield Overland Mail."
It was interrupted by the outbreak of the Civil War on April 12, 1861, because the route passed through Confederate territory.

On the San Francisco postmark date, a stagecoach of this Overland Mail left San Francisco. According to the timetable, the trip took about 24 days to St. Louis. Unfortunately, there is no arrival date noted for this trip. With the travel time of about 24 days, the letter should have reached St. Louis on September 29. From there, the mail was taken by rail to New York. According to the handwritten note in pencil, it reached New York on October 1.
Postage of 10 cents was correct from April 1st, 1855 for a distance over 3,000 miles. The prepayment was compulsory.

Resource:
"Mails of the Westward Expansion 1803 to 1861", Steven C. Walske/Richard C. Frajola