The property was then sold in February 1895, by auction, to Harry C. and Harriet M. Allen of Pasadena. Selling price was $2,600. In October 1895, the Allens sold the property for $5,000 to four men (W. Morgan, J. Vandevort, J. Holmes and W. Staats). These four men then sold the property in December 1895 to the Mt. Wilson Toll Road Company for $76,600.

Although various people used or leased the area, the Mt. Wilson Toll Road Company stayed with the owners until it was purchased by Los Angeles County in 1928. In 1945, additional acreage was acquired from the Federal government by a land swap deal. This last deal brought the total acreage to approximately 232 acres as compared to the original 120 acres.

Use of the Henninger Flats area from 1884 until 1928

From 1884 until 1891, Henninger was the primary occupant of the 120 acre area. He developed the water system and erected lodging. He also planted some trees and gardens. In 1889 the Pasadena and Mt. Wilson Toil Road Company was incorporated. In June 1889, they petitioned to construct the first 4' Toll Road and charged a toll fee for its use. The Road to Mt. Wilson going through Henninger Flats was completed in 1891. In 1892, Henninger was visited by T. P. Lukens and R. J. Busch. With Henninger's permission, Lukens and Busch started the first experimental reforestation in California at the Flats in 1892 by planting some selected conifers.

After Henninger's death in 1894, the area was primarily unoccupied until Lukens came back in 1902. Lukens, who was the first supervisor of the San Gabriel Reserve, discovered that many of the trees he had planted earlier were still alive at Henninger. Due to this survival, without care, and the willingness of the Toll Road Company to provide water and improve the systems, Lukens decided to make Henninger Flats a high elevation nursery. Most of the 51,000 trees that were planted in the San Gabriel and San Bernardino reserve were grown at Henninger during 1903-1907.

With permission from Gifford Pinchot, Lukens signed a lease with the Toll Road Company in October 1903, for the clearing of five acres and the construction of a lath house. In 1904, the widening of the Toll Road commenced with its completion in 1906. It was widened to wagon width. Toll for use was $0.25 by foot and $0.50 by horse. The road was used for access to the Mt. Wilson observatory and Mr. Strain's and Steil's resorts.

During 1903-1907, Lukens and his men planted over 62,000 experimental tree plantings at Henninger. In 1905, the first firebreak in the San Gabriel Reserve was constructed around Henninger in order to protect the site. Due to the success of reforestation at Henninger Flats, Lukens received many orders for seed and seedlings from foresters worldwide. Some of these seed orders came from as far as Chile and Sidney, Australia, as well as from Kansas and all parts of California. Locally, seeds were ordered by Henry E. Huntington, Theodore Payne, Senator Thomas R. Bard and the Mt. Wilson Toll Road Company.

One of the largest plantings supplied by Lukens from the Henninger nursery was 17,000 seedlings for developing the Los Angeles Griffith Park, in 1905. In 1906, George Peavy planted the ridges above Henninger and around the firebreak protecting the site. In 1907, John Muir visited Henninger Flats and was greatly impressed by the work that had been done at the site. Unfortunately, due to its expense to operate, the nursery was moved to Lytle creek in 1907, and closed at Henninger in 1908.

After 1906, Henninger Flats was mainly occupied by lessees; a Japanese family was living there in 1913 raising chickens and a few years later it was used as a fox farm. Although the fox farm, many say, was only a cover to conceal the manufacturing of illegal liquor. In 1917, the famous 100" hooker glass was carefully transported up the Mt. Wilson Road to Mt. Wilson. After its installation, it was the largest full-time telescope in operation in the world.