The first stage in the development of sports cards, during the second half of the 19th century, is essentially the story of baseball cards, since baseball was the first sport to become widely professionalized. Hockey cards also began to appear early in the 20th century. Cards from this period are commonly known as cigarette cards or tobacco cards, because many were produced by tobacco companies and inserted into cigarette packages, to stiffen cigarette packaging and advertise cigarette brands. The most expensive card in the hobby is a cigarette card of Honus Wagner in a set called 1909 T-206. The story told is that Wagner was against his cards being inserted into something that children would collect. So the production of his cards stopped abruptly. It is assumed that less than 100 of his cards exist in this set. The 1909 T-206 Honus Wagner card has sold for as much as $2.8 million.