Hurricane Harvey is the worst rainfall disaster in US history — this interactive map shows how bad it was

On Friday, August 25, Hurricane Harvey hit Corpus Christi, Texas, and then continued on to batter cities and towns along the Gulf of Mexico.

Since then, the tropical storm has killed at least 41 people, damaged or destroyed approximately 20,000 homes, and displaced tens of thousands. Winds have topped 130 mph and downpours reached up to four inches per hour.

On August 30, a rain gauge near Cedar Bayou, Texas, measured 51.88 inches of rainfall, breaking the record for the continental United States set in 1978.

Some climatologists are calling Harvey the worst rainfall event in the country's history.

Business Insider produced an interactive map that shows where the storm struck hardest. Using data from the National Weather Service, the figures below represent the total rainfall from August 24 at 8 p.m. CDT (when it started raining) to August 31 at 4 p.m. CDT.

Hover over a location, and it will show you the rainfall total. We will continue to update the map as more data become available.

"The 3-to-4 day rainfall totals of greater than 40 inches (possible 50 inches in locations surrounding Santa Fe and Dickinson) are simply mind-blowing that has lead to the largest flood in Houston-Galveston history," Houston's National Weather Service office wrote.

A spokesperson from The National Weather Service in Washington, DC told Business Insider that the data was collected by automated gauges as well as reports from volunteers.

During the first 72 hours of the storm, Harvey covered over a 20,000-square-mile area, according to an analysis by Texas-based climatologist John Neilsen-Gammon.

On Wednesday morning, Harvey made second landfall near Cameron, Louisiana as a tropical storm with winds up to 40 mph. Forecasters expect an additional 3 to 6 inches of rain in eastern Texas, southwestern Louisiana, and parts of Kentucky by Friday, with some areas to get up to 10 inches.

Floodwater has overwhelmed many areas in Houston, due partially to the city's flat geography, outdated (and in some areas, blocked) drainage systems, and a recent construction boom that has eliminated over 38,000 acres of wetlands.

At least 33,000 people in Texas have fled to more than 230 shelters, with 11,000 people inside Houston's largest sports stadium. Hundreds of thousands could seek some kind of disaster assistance, officials said.

Note: The National Weather Service is still reviewing Harvey rainfall totals.