Excerpted from: 
Chapter 2 
Dating Soft Drink Bottles 
© Bill Lockhart 2000

http://alamo.nmsu.edu/~lockhart/EPSodas/Chapter1-4/chap2.htm

 The solution to the problem of the need for enforced return was the paid deposit.  The idea of a standard deposit on bottles was discussed at the annual meeting of the American Bottlers' Protective Association in 1901, and was endorsed by the Association in 1902.  Paid deposits, however, were not universally brought into effect until the late 1920s Paul & Parmalee 1973:25).  In 1934, the National Recovery Administration required mandatory deposit of 2¢ per small bottle and 5¢ for larger (usually quart size) containers (Woodroof & Phillips 1974:199).  Although the amount of deposit varied at different times and locations, the outlay of money was sufficient to ensure that most people would return the containers.  Because proof of purchase was not required in order to redeem returnable bottles, there was great incentive for children and unemployed adults to collect discarded bottles and insure a fairly steady continuing cycle.  In an attempt to educate the public, early bottlers often embossed their bottles with messages, such as THIS BOTTLE IS NEVER SOLD or RETURN FOR DEPOSIT.  This method was deemed so effective by many bottlers that it continued in use until the 1980s.