In 1894, Asa Candler the druggist and Atlanta business man came up with the idea to distribute hand written tickets for a free glass of his tonic named "Coca-Cola." By 1895 Candler announced to shareholders that Coca-Cola was served in every state in the United States.
Also in 1895, grocer C.W. Post began using coupons to help sell groceries. His coupon gave people a one cent discount on his new breakfast cereal, Grape Nuts.
During the 1930's, coupons became a staple in American households because of the Great Depression.
By the 1940s chain supermarkets began to sprout across the country and continued the tradition of using coupons developed by smaller neighborhood grocery stores.
In 1957, the Nielsen Coupon Clearing House became the first clearing house devoted to coupon redemption. This marked the beginning of the coupon industry.
In 1965, it was reported that half of all American households were clipping coupons.
By the mid 1990's, retailers began distributing printable coupons on the internet.
In the early 2000's, online coupons became wildly popular in the form of coupon codes. One of the most popular online coupons is the free shipping coupon.
In 2005, Cellfire became the first nationwide mobile coupon and discount offer service that allows consumers to easily access deals from brand-name merchants through their cell phone.
In 2008, Cellfire became the first company ever to tie a mobile phone to a point of sale system. Consumers can browse and save coupons directly from their phones.

Within two decades one in every nine Americans had received a free Coca-Cola soft drink.
Sources
http://www.couponmonth.com/pages/allabout.htm
http://en.wikipedia.org/wiki/Coupon
http://www.freeshipping.org/blog/history-of-coupons/