Pickwick Stage Corporation
"The taxicab carried him [Sam Spade] to the Pickwick Stage terminal in Fifth Street. 
He checked the bird at the Parcel Room there, put the check into a stamped envelope, wrote M. F. Holland and a San Francisco Post Office box-number on the envelope, sealed it, and dropped it into a mail-box. From the stage-terminal another taxicab carried him to the Alexandria hotel." from Dashiell Hammett's The Maltese Falcon, the 2012 Big Read title.
Springfield has a connection to Dashiell Hammett's "Maltese Falcon" through one of its early bus services. In 1927, the Pickwick Stage Corporation (the bus line mentioned above) inaugurated a trans-continental bus service over Route 66 from Springfield to Los Angeles. Springfieldian passengers, therefore, could ride a Pickwick Stage Company bus west to Los Angeles, transfer to another bus, and ride north to the San Francisco bus station. There, they could stay overnight at the Pickwick Stage Company’s hotel on the corner of Mission and Fifth Streets.
East and West Busses Meet: Daily service inaugurated between St. Louis and Los Angeles. Springfield, Mo., Leader, 2 November 1927, page 18.
"For the first time in history the Far West and the Middle West were connected by a single bus line yesterday when the Pickwick Stage Company inaugurated its trans-continental line between St. Louis and Los Angeles which will be conducted daily.
"Busses from St. Louis and Los Angeles met at the Pierce Oil Company's service station on St. Louis Street. Each bus bore eight passengers and official[s] of the company.
"Both busses will meet here daily at 3:45 p.m.
"The route of the line is the 'Main Street of America.' The principal cities through which it passes are Springfield, Carthage, Joplin, Tulsa, Oklahoma City, Amarillo, Texas; El Paso, Texas; Phoenix, Arizona; and then Los Angeles. The trip from St. Louis to Los Angeles takes close to 60 hours.
"The company now has no permit to carry passengers from one Missouri point to another. However, it may carry Missouri passengers to points outside of the state.
"T.A. Bacon is the traffic manager for the Springfield division."
According to a later Springfield Leader article dated February 16, 1928, page 1, the Pickwick Corporation merged with the Greyhound Bus System. With the merger the '...new transportation system will be known as the Pickwick-Greyhound system and will provide a complete coast to coast line. The Pickwick corporation has operated busses from Chicago to Los Angeles, while the Greyhound company has confined its operations to the east'.
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