The 1872 Powder Works Bridge is a historic covered bridge in Santa Cruz, California. It is a Smith truss bridge, built across the San Lorenzo River for the California Powder Works, an explosives manufacturer whose factory complex stood on the riverbanks. It is currently owned and maintained by the Paradise Park Masonic Club, and is open to pedestrian and vehicular traffic, with a posted weight limit of 5 tons.

Just downstream of the Henry Cowell Redwoods State Park, this Smith truss bridge has a single span, with a total structure length of 180 feet (55 m) and a span length of 163 feet (50 m). It has a roadway width of 19 feet 3 inches (5.87 m). Its trusses are built out of Douglas fir, and its roof is corrugated metal. The exterior is clad in vertical board-and-batten siding.

The bridge was constructed by the Pacific Bridge Company, with its major elements manufactured at a plant in Alameda, and was installed in 1872. The California Powder Works operated on this site between 1863 and 1914, after which the site was largely demolished and abandoned. The property was purchased by a Masonic organization from Fresno and developed as a summer colony they dubbed "Paradise Park".

The bridge is one of 23 known historic examples of a Smith truss remaining in the United States, and is the longest and among the best-preserved, as determined by a nationwide survey conducted by the National Park Service. This truss type was marketed on a nationwide scale by the Smith Bridge Company and was briefly competitive with iron bridges.

The discovery of gold in California in 1848 created a growing demand for blasting powder for mining and railroad construction. Powder imported from the East Coast was expensive, and when the Civil War threatened to eliminate the supply of blasting powder, a group of San Francisco businessmen formed the California Powder Works in 1861.

In 1862, the company purchased this site on the San Lorenzo River, which offered water power, timber (for charcoal and kegs, and fuel), proximity to transportation, a labor force, and relative seclusion for safety. In 1863, California Powder Works built twenty-five buildings in Powder Mill Canyon. The company expanded in 1867 and again in 1872 when the covered bridge was assembled across the San Lorenzo River.

By 1879, the site contained approximately seventy-five buildings, including twenty-one powder mills, ten shops, ten wheelhouses, a boarding house, and a school. Eventually, a village of about one hundred residents occupied a site south of the Powder Works.

By 1887, California Powder Works yielded four million pounds of powder annually and was the largest producer of explosives west of the Mississippi River for half a century.

Then in 1903, the DuPont Corporation purchased a controlling interest and changed the name from California Powder Works to E. I. DuPont de Nemours Powder Company. But in 1912, DuPont holdings were broken up under the Sherman Antitrust Act. The powder company was reorganized as the Hercules Powder Company and moved to a modern facility in the town of Hercules, where operations continued until 1955.

Powder Works Bridge was designated a National Historic Landmark in 2015 as one of the best-preserved national examples of the Smith truss.

Located at:  N37 00.49   W122 02.67       -       WGCB #05-44-03

Photographed in May of 2025

Photos by Millard Farmer