(CBS) — As Hurricane Harvey moved slowly out of Texas and into Louisiana on Wednesday, it is simply hard to describe its epic proportion.

Here are five mind-boggling things to consider:

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1) In some places, Harvey dumped more than 50 inches of rain–shattering storm records for the continental United States. Typically, it takes more than a year (13 to 14 months to be exact) for Chicago to get that much rain, according to an interactive map published by the New York Times. You can enter a ZIP code to see how long it would take a particular area to get that much moisture. Is some areas of the United States, it takes years.

2) According to published reports about 30 percent of Harris County, which includes Houston, is under water. That’s about 530 square miles–more than twice the size of Chicago.

3) Forecasters estimate Harvey dumped about 15 to 20 trillion gallons of water across Texas. The Chicago area’s flood control system–the Deep Tunnel–has three reservoirs. One of those is in McCook that will hold about 10 billion gallons of water when complete in 2029. That means Harvey would fill McCook 1,500 to 2,000 times over. (The reservoir in Thornton, along Interstate 294, can hold about 8 billion gallons.)

4) Over 15 hours, officials said there were 56,000 calls made to 911 in the Houston area. Typically, they handle about 8,000.

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McCormick Place

McCormick Place (CBS File Photo)

5) More than 10,000 people have taken refuge inside the Houston convention center. That space is roughly the equivalent to three McCormick Place Lakeside Centers. (Overall, the total space offered by the McCormick Place campus is much larger than Houston–by about one million square feet.)

People seek shelter at the George R. Brown Convention Center in Houston. (Credit: Jabin Botsford/The Washington Post via Getty Images)