He was a successful physician and territorial justice in Waukesha, Wisconsin, but left there for California in the early 1830's where he settled in Placerville. His trip overland, which he made in his own carriage with his wife, accompanied by a train of eleven wagons, as not without incident. One adventure he often related concerned a meeting with marauding Paiute Indians. Undaunted, he faced them and removed and held up first his upper teeth and then his lower plate. The redskins were so astounded by the white man's magic that they turned and fled. On this long trip he maintained his professional dignity by wearing a long redingote, while his wife took her place beside him dressed in flounced petticoat, colored silk dresses and red morocco shoes. He married secondly a widow Sophia Story in Wisconsin, but they separated and he returned to Placerville, California. He was a part owner of the Schaeffer Copper, Gold and Silver Mine in the Middletown Mining District. He died of sunstroke.

Van Vleck, California is an unincorporated community in El Dorado County. It is located four miles east-northeast of Pollock Pines, at an elevation of 3,888 feet. It is the western slope of the Sierra, which is mostly United States Forest land. At one time there were several families who would bring their cattle to the high mountain to graze during the summer months. They had to secure grazing permits to do so. Over time their name would become associated with the area where they were assigned to graze cattle. It was named after the descendants of Dr. Harmanus Van Vleck, Jr., who are still living in El Dorado County, Sacramento County and Amador County.

Van Vleck Ranch is a full-service equestrian facility located at the Murieta Equestrian Center on Van Vleck Raod in Rancho Murieta, California. Since 1856 it was established and is currently owned by the California-born descendants of Dr. Harmanus Van Vleck, Jr., whose family has been committed to the land, the environment and the community. It started as a couple hundred acres and over time has expanded to over 5,000 acres. Their ranching resource operations are all reflective of their proud part in California's history and ensuring its bright future.

Van Vleck Bunkhouse, built in 1957, is nestled in a red fir forest on the edge of a meadow. It is all that remains of the Van Vleck Ranch site, which from the 1860's to the 1960's operated as a cattle ranch. It is located at El Dorado National Forest in Northern Sierra Nevada, California.

• https://www.findagrave.com/memorial/136444718/harmanus-van_vleck