During the Prohibition years of 1920 to 1930, George Cassiday served as Congress's primary bootlegger.

Cassiday's career began after his return from serving in the U.S. Tank Corps during World War I. A friend asked if he could acquire alcoholic beverages for two House members—unsurprisingly, both of them had voted in favor of Prohibition. Soon, Cassiday was averaging 25 deliveries a day, transporting bottles of booze to House and Senate offices in a large, clinking briefcase.
Capitol Police recognized Cassiday by his trademark emerald green hat, and allowed him access to the Capitol at all hours to supply thirsty legislators.
Eventually, Cassiday ran afoul of some of the few politicians still firmly opposed to alcoholic drinks. Officials arranged a sting operation, dispatching an undercover Prohibition Office agent who would later become known as The Dry Spy.
The Dry Spy lived at what is now called Prohibition House. To find the coordinates of the physical cache (the final stage of this two-part multi), input the real name of The Dry Spy as shown on the sign outside Prohibition House:

You can validate your puzzle solution with certitude!
Happy caching, and Cheers!