Warning: The following contains SPOILERS for Legends of Tomorrow, season 5, episode 4, "Slay Anything."
"Slay Anything," the latest episode of Arrowverse. Strangely enough, no episode of The Flash ever revealed which state Central City was located in before now.
Central City's location has been a mystery for six seasons and the subject of some conflict. The pilot episode of The Flash said that it was 600 miles from Star City and the two cities shared Iron Heights Penitentiary as their closest maximum security prison. Yet Central City was also said to be somewhere in the American Midwest and had a ZIP Code which suggested it was Star City to be located in the Pacific Northwest of Earth-Prime, but gave no general location for Central City.
Legends of Tomorrow confirmed where Central City was located in a surprising and twisted way. "Slay Anything" opened with a flashback detailing the death of serial killer Freddy Meyers (aka The Prom Night Slasher) and how he was executed in 2004, 15 years after he apparently murdered several of his classmates on the night of their Senior Prom. As Freddy's body was being transported back to Central City for burial, a tag on his body bag confirming that Central City was in Missouri was visible.
In the original post-Crisis Universe of DC Comics' books, Central City was depicted as being in Missouri. It often varied, however, as to what real-world city Central City was meant to resemble. DC Comics' major cities were often meant to mirror various real-world locations. This can also be seen in the Arrowverse, with Batwoman's Gotham City being modeled on Chicago.
Some issues of The Flash depicted Central City with a large arch, similar to the Gateway Arch of St. Louis. A similar arch can also be seen in Central City in the Young Justice animated series. However, most comics seemed to view Central City and its neighboring metropolis of Keystone City as the DC Comics' equivalent of Kansas City, Missouri and Kansas City, Kansas; two large cities separated by the merging of two rivers. on a state boundary line. Amusingly, most of the city photography used to depict Central City in Legends of Tomorrow and the other Arrowverse shows was filmed in Portland, Oregon.