[1] Newmark contributed to developing many local institutions, such as the Los Angeles County Library and others supporting children's welfare.

He wrote a memoir, Sixty Years in Southern California: 1853–1913,[2] which has been cited in dozens of academic papers and books.

After he reached Los Angeles, his first American job was serving as a clerk for his brother Joseph at his partnership Rich & Newmark, a dry goods emporium.

At the time, Newmark had limited English-language skills; he spoke German, Swedish, and had picked up some Spanish while en route to and in California.

Newmark lived with them for a time, and his aunt taught the young man how to read, write, and spell in English.

[7] At the end of 1885, Newmark retired from the grocery business to devote more time to his real estate and investment pursuits.

[1] The land had been owned by an Italian settler named Alessandro Repetto, who had bequeathed the ranch to his brother Antonio.

[8] In May 1899, Newmark subdivided the tract owned by him and his nephew, after contracting with William Mulholland to design and construct a suitable water system for the new settlement.

[8][10] A piece of this tract, adjacent to the tracks of the San Pedro, Los Angeles & Salt Lake Railroad, was developed into a town site called Newmark.

[1][14] Newmark's memoir, Sixty Years in Southern California, was assembled with the assistance of his sons and a Pasadena historian.

It has been called "one of the great autobiographies" by an American Jewish writer, and "the single most valuable memoir" about southern California in the nineteenth century.

Now called the New Mart building, the edifice was the first high-rise structure in the city, and was built in 1928 by Newmark's sons.