A lot of companies either were never successful or went bankrupt, so that their certificates became worthless pieces of paper until the hobby of scripophily began. The mining boom in the 1850s, railroad construction in the 1830s, the oil boom in the 1870s, telegraphy (1850s), the automobile industry beginning around 1900, aviation (around 1910), electric power and banks in the 1930s, the airline wars and mergers in the 1970s, cellular telephones (1980s), long distance telephone service in the 1980s and 1990s, and most recently the Dot-com era and Enron all resulted in historically significant certificates being generated and issued.