First set aside as part of the Pinnacles Forest Reserve in 1906, Pinnacles has had several different federal management agencies, ranging from the U.S. Forest Service to the General Land Office and ultimately to the National Park Service.
In 1908 President Theodore Roosevelt created Pinnacles National Monument with the power given him in the Antiquities Act of 1906.
The initial area designated under the Antiquities Act was 2,080 acres (840 ha).
The Forest Service relinquished control of the monument circa 1911, but no operating agency yet existed to receive it.
No drivable roads existed into the park from communities like Hollister.
Hollister boosters campaigned for federal funds for road-building.
Congressman Everis A. Hayes made a trip into the Pinnacles in 1913 as part of the campaign for road funds.
By 1914, primitive roads extended to Bear Valley.

The National Park Service was finally established in 1916, but Pinnacles was not considered significant enough to command any Park Service resources at that time.
In the meantime, a mining claim disrupted access to the traditional picnic grounds.
In 1922, following repeated pleas from local residents for Park Service action, W.B. Lewis, superintendent of Yosemite National Park, was directed to visit Pinnacles and report on the circumstances to Park Service director Stephen Mather.
Lewis had a difficult trip and stayed only 45 minutes, and his report included a recommendation that the monument be abandoned, since the most scenic sections were in private hands.
The General Land Office, which administered lands surrounding the national monument and what was then known as Monterey National Forest, also received complaints, and in December 1922, J.H. Favorite of the GLO made a thorough report which was copied to Mather.
Favorite recommended that public-domain lands be consolidated into the monument, and that a caretaker be appointed from a local homestead.
In 1923, Herman Hermansen was appointed caretaker, and on May 7, 1923, the monument was enlarged by proclamation of President Warren G. Harding.

Mather finally visited the monument on March 28, 1924.
A further proclamation, this time by Calvin Coolidge, enlarged the monument on July 2, 1924, securing water sources and campsites, was followed by a directive for a complete survey of the now-2,973-acre (1,203 ha) monument.
Following a visit by NPS assistant director Horace M. Albright, money was appropriated to build a ranger's cabin, completed in 1929, while facilities within the caves were improved.
Frank A. Kittredge, the Park Service chief of engineering, and Thomas Chalmers Vint, Park Service landscape architect, conducted a survey for a five-year improvement plan in 1927.
In 1929, condemnation proceedings were filed against private landowners in and around the park, including the mining company, seeking 1,286.27 acres (520.54 ha).
An expansion proclamation by President Herbert Hoover in 1931 added 1,926.35 acres (779.57 ha) of land donated by San Benito County.
Trail building was expanded in the early 1930s, including a tunnel for the High Peaks Trail.

In 1933, a Civilian Conservation Corps camp was established for about 200 men who worked on additions to the trail network.
After lengthy legal proceedings, the old mining claims were incorporated into the monument in 1958.
CCC laborers improved the road in Bear Gulch, built tourist cabins, and constructed the dam at the Bear Gulch reservoir.
A fire lookout was built by the CCC on Chalone Peak in 1935, but was destroyed by fire in 1951 and replaced by a frame structure the following year.
The park's visitor center and headquarters were built in 1936–37 from local stone.
A superintendent's residence was started in 1941 and completed in 1949.
The Mission 66 project added lands and new projects, with an emphasis on development of the previously undeveloped west side of the park.

In 1975, the park comprised 16,721 acres (6,767 ha), growing to the present 26,606 acres (10,767 ha) through a series of additions including the 2,000-acre (810 ha) Pinnacles Ranch.
 The most recent add
First set aside as part of the Pinnacles Forest Reserve in 1906, Pinnacles has had several different federal management agencies, ranging from the U.S. Forest Service to the General Land Office and ultimately to the National Park Service. In 1908 President Theodore Roosevelt created Pinnacles National Monument with the power given him in the Antiquities Act of 1906. The initial area designated under the Antiquities Act was 2,080 acres (840 ha). The Forest Service relinquished control of the monument circa 1911, but no operating agency yet existed to receive it. No drivable roads existed into the park from communities like Hollister. Hollister boosters campaigned for federal funds for road-building. Congressman Everis A. Hayes made a trip into the Pinnacles in 1913 as part of the campaign for road funds. By 1914, primitive roads extended to Bear Valley.
The National Park Service was finally established in 1916, but Pinnacles was not considered significant enough to command any Park Service resources at that time. In the meantime, a mining claim disrupted access to the traditional picnic grounds. In 1922, following repeated pleas from local residents for Park Service action, W.B. Lewis, superintendent of Yosemite National Park, was directed to visit Pinnacles and report on the circumstances to Park Service director Stephen Mather. Lewis had a difficult trip and stayed only 45 minutes, and his report included a recommendation that the monument be abandoned, since the most scenic sections were in private hands. The General Land Office, which administered lands surrounding the national monument and what was then known as Monterey National Forest, also received complaints, and in December 1922, J.H. Favorite of the GLO made a thorough report which was copied to Mather. Favorite recommended that public-domain lands be consolidated into the monument, and that a caretaker be appointed from a local homestead. In 1923, Herman Hermansen was appointed caretaker, and on May 7, 1923, the monument was enlarged by proclamation of President Warren G. Harding.
Mather finally visited the monument on March 28, 1924. A further proclamation, this time by Calvin Coolidge, enlarged the monument on July 2, 1924, securing water sources and campsites, was followed by a directive for a complete survey of the now-2,973-acre (1,203 ha) monument. Following a visit by NPS assistant director Horace M. Albright, money was appropriated to build a ranger's cabin, completed in 1929, while facilities within the caves were improved. Frank A. Kittredge, the Park Service chief of engineering, and Thomas Chalmers Vint, Park Service landscape architect, conducted a survey for a five-year improvement plan in 1927. In 1929, condemnation proceedings were filed against private landowners in and around the park, including the mining company, seeking 1,286.27 acres (520.54 ha). An expansion proclamation by President Herbert Hoover in 1931 added 1,926.35 acres (779.57 ha) of land donated by San Benito County. Trail building was expanded in the early 1930s, including a tunnel for the High Peaks Trail.
In 1933, a Civilian Conservation Corps camp was established for about 200 men who worked on additions to the trail network. After lengthy legal proceedings, the old mining claims were incorporated into the monument in 1958. CCC laborers improved the road in Bear Gulch, built tourist cabins, and constructed the dam at the Bear Gulch reservoir. A fire lookout was built by the CCC on Chalone Peak in 1935, but was destroyed by fire in 1951 and replaced by a frame structure the following year. The park's visitor center and headquarters were built in 1936–37 from local stone. A superintendent's residence was started in 1941 and completed in 1949. The Mission 66 project added lands and new projects, with an emphasis on development of the previously undeveloped west side of the park.
In 1975, the park comprised 16,721 acres (6,767 ha), growing to the present 26,606 acres (10,767 ha) through a series of additions including the 2,000-acre (810 ha) Pinnacles Ranch.  The most recent add
Pinnacles National Park