Biohazard Cleanup Near Downtown Weldon Spring Weldon Spring, MO

Weldon Spring is a city in St. Charles County, Missouri, about 30 miles west of St. Louis in the metro area's fast-growing western suburbs.

Weldon Spring is named for the spring beside the log home that North Carolina frontiersman John Weldon built overlooking it in 1790.

Weldon Spring was platted in 1864, and its post office operated from 1875 until 1957.

Weldon Spring had a population of 5,326 at the 2020 census.

At the 2010 census Weldon Spring had 5,443 people living in 2,050 households.

Weldon Spring's population exploded during the 1990s, jumping from 1,470 people in 1990 to 5,270 in 2000, a gain of more than 250 percent.

In 1941 the United States Army bought about 17,000 acres around Weldon Spring and built the Weldon Spring Ordnance Works, the largest explosives factory in the United States, producing TNT and DNT for the Allied war effort.

The ordnance works closed on August 15, 1945, just days after the end of World War II, and most of the land was then sold off.

In 1945 the Weldon Spring area was even proposed as a site for the headquarters of the new United Nations.

The Atomic Energy Commission later ran a uranium-ore processing plant on part of the old ordnance site from 1957 to 1966, leaving a federal cleanup site that the Department of Energy still manages today.