Forty years later, records from Tropical Storm Agnes still stand.
But the records barely tell the story. As measured at BWI Marshall Airport, June 1972 saw a record 9.95 inches of rain. June 21 and 22, meteorologists measured 2.19 inches of rain and 3.84 inches of rain, respectively. BWI, known as Friendship Airport at the time, reported a "surprisingly low" rain total of 6.62 inches from Agnes, according to a Sun article June 30, 1972.
Elsewhere, the rain approached 15 inches. Entire towns braced for floodwaters to top dams, and 21 people died across the state, according to Sun archives.
In Baltimore City, the Gwynns Falls washed over roads and bridges and flooded homes near Windsor Mill Road, according to Sun archives. On Russell Street, a motel was evacuated because the building was at risk of collapsing, while massive gas tanks at the nearby Sun Oil Co. terminal broke from their foundations and floated around. The Jones Falls valley as far north as North Avenue was evacuated, ordered by Mayor William Donald Schaefer.
In Baltimore County, more gas tanks were swept away and leaked hundreds of gallons of fuel. The Dulaney Valley Road bridge over Loch Raven reservoir was said to be in imminent danger of collapsing and was closed.
Major arteries like Route 40 and Route 29 in Howard County were closed and impassable, with 12 feet of standing water in Ellicott City.
Westminster received some of the heaviest rains, 15 inches according to the National Weather Service, with 9.5 inches that fell June 22 the greatest rainfall ever recorded on a June day in Maryland, according to Sun archives.
The towns of Union Bridge and Linwood in western Carroll County were "completely cut off and surrounding by flooding waters," according to the Sun, with one main bridge having been washed away. "Virtually all secondary bridges were reported washed out," the Sun continued, as well as the Main Street bridge into Sykesville.
While the flooding was considered a so-called "100-year flood" for much of the state, one Hopkins professor told the Sun a year later it was more like a 300- or 400-year flood for the Susquehanna River.
A year after the storm, many were still rebuilding from the destruction, which cost $75 million in Maryland in 1972 dollars -- nearly $400 million today.
Read some fascinating personal accounts of the flooding's fury in Ellicott City, Laurel and Catonsville, as reported in the Sun's community newspapers. Agnes shaped how Howard County responds to flooding in Ellicott City and elsewhere today.
Do you have any memories of Agnes? Share them by e-mailing email@example.com or tweeting @MdWeather.