When the Board of Park and Boulevard Commissioners proposal reducing the size of the park because of the expense, the ever active citizens of the Penn Valley Park area actively opposed the reduction. The Board then changed its recommendation, increased the acquisition to a total of 131.92 acres, and changed the original boundaries.

The land taken for the park was occupied by some 300 houses, most of them very dilapidated. Cost of acquisition was $870,759.60. George E. Kessler, landscape architect for the system, threw an earth dam thirty feet high across the northwest section, partly filled the basin thus created with earth, and allowed the water to spread over the rest, forming a pretty artificial lake. Drives with macadam roadbeds wound for over three miles through the park. In places where the roads had to be cut into limestone cliffs, the stone was prevented from sliding by specially constructed masonry foundations designed to blend with the rocky ledge above.

The status of Penn Valley Park was reported in the1920 Souvenir booklet on The Park and Boulevard System of Kansas City, Missouri. A branch of the Santa Fe Trail from Kansas City, known then as Westport landing, to Westport, passed through the park. Kessler split the roadway into two parts with a median. The west side was for slower, residential vehicles that connected on the south end with Broadway. The east side was for commercial vehicles that went over to Main Street at the south end. The Operating Plant for the West Park District, located near 30th and Central Streets, was completed in 1910. The 10 acres in the northwest corner of the park was to be devoted to playground activities. A large field house with administrative offices, shower baths, swimming pool, 60×102 feet; gymnasium and assemble rooms was planned. The swimming pool and central unit of the field house was built in 1916. This playground, when completed, was to be one of the best and most fully equipped playgrounds in the City. The baseball diamond was used continuously during the season. The park contained eight tennis courts, which were used by about 400 people per day. Three separate sections were set aside for children’s playgrounds, and were supervised in the summer time. By 1920 construction costs had reached $402,710.11 and $239,389.81 had been spent on maintenance.