Bootleg mining

Bootleg mining or shoemaker mining is a form of illegal coal mining.
The term originated around the 1920s, though the practice probably predates that. Generally, a bootleg mine (sometimes called a bootleg pit) is a small mine dug by a handful of men. Often this took place surreptitiously on land owned by somebody else, such as a coal company. They were frequently dug by coal miners off official tunnels in order to procure additional, free coal for themselves, a practice that causes additional ramifications when fighting mine fires. Sometimes small pits are hidden under houses or outbuildings. Usually, the mine is not large enough to turn around in. The pits are known for being unsafe, and often causing collapse.
The practice has died away in the United States; an American with simple equipment cannot dig enough coal in a day to reach a living wage. Bootleg mines in China are still very common, as are the fatalities resulting from unregulated mining.
In Pennsylvania.
Shortly before the Great Depression, Pennsylvania's anthracite industry collapsed, shutting down collieries and throwing tens of thousands of miners out of work. Unemployed miners dug their own coalholes, often on company property, and began setting up bootleg breakers and trucking operations, creating an entire bootleg coal industry. According to a 1938 report commissioned by Governor George Howard Earle, there were as many as 1,965 bootleg holes, operated by over 7,000 bootleg miners, producing 2,400,000 tons of coal per year. By 1941, miners and police clashed over the dynamiting of their coalholes.