During the 1930s and later, it was common for telephone prefix numbers to use the first two letters of a name. The song title was the telephone number of the Hotel Pennsylvania , at 7th and 33rd in New York City, which served as Glenn Miller's home base during his many month tenure at the hotel's Cafe Rouge beginning January 1940. The hotel was built by the Pennsylvania Railroad, across the street, to go with the Pennsylvania Station ("You leave the Pennsylvania Station 'bout a quarter to four..." from "Chattanooga Choo-Choo"). In recent years, the hotel was the Statler Hilton but has re-emerged, once again, as the Hotel Pennsylvania. Through all the years, the phone number has remained the same -- 736-5000 or PE 6-5000.