In 1911 the building was expanded 26' to the south, giving it the current 54' by 28' dimensions. The construction methods, materials and most details inside and out were carried out in this new addition increasing the number of cells upstairs and providing living quarters for the jailer and his family, as well as an entry foyer. Narrow and steep metal stairs lead to the cells on the second level. The upper floor is concrete supported by concrete beams dividing the structure into four equal bays with one concrete column in the center.
After the wooden courthouse and several other buildings burned in March of 1915, it was determined that the new courthouse be built at a different location about four blocks to the south. The merchants soon discovered that people attending business at the new courthouse no longer visited the original town square, so within a short time all the businesses migrated to the new square. By 1923, Coldspring was firmly entrenched in its new location. Except for the jail, the old square, which had been the heart of early Coldspring and San Jacinto County, was forgotten and neglected.
By 1980, the building was deemed no longer within acceptable limits of jail standards, and was abandoned for this function in favor of a modern facility at another location. The San Jacinto County Historical Commission was granted a 100 year lease on the property by the Commissioners. Monies were raised through grants, donations and fund raisers to undertake a reconstruction and adaptive reuse of the old jail. These efforts were successful and the old jail now serves the county and thousands of visitors each year as the Old Jail Museum. The Old Jail Museum houses artifacts pertaining to the history of the East Texas and San Jacinto County are. The Old Jail Museum boasts both Texas Historical Commission and National Register recognition.