The Timothyberg side of the mountain was regularly burned over by blueberry pickers every year through 1916, the year the state built the 47-foot (14 m) fire lookout tower on the mountain and extended the old board road to make it accessible for observers coming by vehicle.
It replaced another tower that had briefly stood on Slide Mountain, the Catskills' highest peak, a few years earlier.
Tremper was chosen since it offered views of the lowlands that could not be seen so easily from the fire towers on Hunter and Belleayre mountains.

In 1921 the state bought more of the mountain, allowing it to designate the road as a hiking trail.
By 1931 it had been extended beyond the tower as a footpath, descending the northeast side of the mountain into Hoyt Hollow to Willow.
Later in the 1930s a lean-to was built at the summit for backpackers to camp in.

This trail system remained unchanged for most of the mid-20th century, save for the construction of a new lower section of trail and a trailhead about 0.3 mile (500 m) east of the foot of the road just outside Phoenicia.
When the dormant idea of the Long Path was revived in the 1960s, the trail over Tremper was included.
A wayward campfire led in 1966 to a wildfire that burned 10 acres (4 ha) just below the summit.
Four years later the state closed the tower.

In 1976 the state purchased some more land along the trail and built another lean-to at 2,100 feet (640 m), along the trail below the summit.
The next year the tower's two support structures, the observer's cabin and a storage shed, were removed.
These were the last significant changes to facilities on Tremper for two decades.

At the end of the century interest in restoring and preserving the fire tower led to a local fundraising campaign after DEC proposed to remove it as a structure incompatible with the Forest Preserve.
It was reopened in spring 2001 and listed on the National Register in late 2001.
A new extension of the Long Path along the ridge past Carl Mountain to Plateau Mountain was opened that year as well.
The Timothyberg side of the mountain was regularly burned over by blueberry pickers every year through 1916, the year the state built the 47-foot (14 m) fire lookout tower on the mountain and extended the old board road to make it accessible for observers coming by vehicle. It replaced another tower that had briefly stood on Slide Mountain, the Catskills' highest peak, a few years earlier. Tremper was chosen since it offered views of the lowlands that could not be seen so easily from the fire towers on Hunter and Belleayre mountains.
In 1921 the state bought more of the mountain, allowing it to designate the road as a hiking trail. By 1931 it had been extended beyond the tower as a footpath, descending the northeast side of the mountain into Hoyt Hollow to Willow. Later in the 1930s a lean-to was built at the summit for backpackers to camp in.
This trail system remained unchanged for most of the mid-20th century, save for the construction of a new lower section of trail and a trailhead about 0.3 mile (500 m) east of the foot of the road just outside Phoenicia. When the dormant idea of the Long Path was revived in the 1960s, the trail over Tremper was included. A wayward campfire led in 1966 to a wildfire that burned 10 acres (4 ha) just below the summit. Four years later the state closed the tower.
In 1976 the state purchased some more land along the trail and built another lean-to at 2,100 feet (640 m), along the trail below the summit. The next year the tower's two support structures, the observer's cabin and a storage shed, were removed. These were the last significant changes to facilities on Tremper for two decades.
At the end of the century interest in restoring and preserving the fire tower led to a local fundraising campaign after DEC proposed to remove it as a structure incompatible with the Forest Preserve. It was reopened in spring 2001 and listed on the National Register in late 2001. A new extension of the Long Path along the ridge past Carl Mountain to Plateau Mountain was opened that year as well.
Mount Tremper