Rich gold diggings in the Elkhorn Mountains of Eastern Oregon drew 5,000 residents to the town of Sumpter in the early 1900s. At its height, Sumpter claimed plank sidewalks, seven hotels, 16 saloons, three newspapers, two churches, an opera house and a red light district.

A fire in 1917 burned much of the city. Today, about 175 people call Sumpter home, but the population booms during flea market events held on Memorial Day, Fourth of July and Labor Day weekends.

The year-round daily attraction in Sumpter is the gold dredge that recovered about 128,570 troy ounces from the Powder River Valley, worth about $180 million at current prices. The Sumpter Valley Dredge State Heritage Area covers 93 acres and sees more than 15,000 visitors each year.

The last of three dredges that traveled about 8 miles across the valley starting in 1913, Sumpter No. 3 was constructed in 1935 from pieces of the second dredge, which had sat idle for a decade. Sumpter No. 3 operated until 1954.

The dredge was added to the National Register of Historic Places in 1971. Restoration work began in 1995, and the state acquired the site and associated equipment and buildings for a park after that.

The principle of dredge mining is efficiency gained through volume, but it cost more to run Sumpter No. 3 than the gold could pay for, and the company was $100,000 in debt when it shut down.

It took three men to operate the machinery and another 17 for maintenance, bookkeeping, surveying, truck driving, management and other roles.

On the outside, a mining dredge resembles a boat floating on a pond of its own making. Projecting from the bow is a boom with 72 one-ton buckets that dug up the countryside at the rate of 20 buckets per minute. Another boom at the stern deposited tailings across the landscape that, seen from the air, resemble worm castings and can be seen for miles along State Route 7.

Inside the dredge, electrically powered machinery duplicated on a larger scale the same processes used by placer miners during the gold rush across the West. Large rocks and gravel were sifted, sorted and separated from finer minerals and then washed over a series of riffles, where gold settled and was trapped.

A film crew shot footage of Sumpter No. 3 for an episode in the 2013 television series “Ghost Mine” about a phantom called Joe Bush. Dredge workers claimed to have seen wet footprints, flickering lights and doors opening and closing on their own.

The name Joe Bush does not appear in company records, but in 1918 an oiler named Chris Rowe was crushed in the gearbox of Sumpter No. 1, and the story goes that his spirit may have ended up inside the third dredge — along with equipment from the earlier dredges.

To reach the historic dredge from John Day, drive east on Highway 26 to Austin Junction, follow State Route 7 for 25 miles, turn left on State Route 410 and drive about 4 miles to Sumpter.

The state park is open May 1 through Oct. 31 from 8 a.m. to 7 p.m. daily. Guided tours, gold panning lessons and other programs are offered on weekends.

Admission to the park is free. For more information, call 541-894-2472 or visit historicsumpter.com.