The size of mines has grown in lockstep with improvements in the quality and size of equipment. Due to the dispersion of fixed costs over greater tonnages, this allowed for the introduction of bigger and far more productive equipment while also assisting in the reduction of production unit costs. Scale in mining is much the same as mass output in the manufacturing industry.

There is little uncertainty that mines have gotten bigger overall over time, but it is difficult to get data to demonstrate and quantify this throughout the industry. Industry-level data before this is sporadic, and databases describing the operation and costs of the mining industry only really began to become available in the 1970s. This may not be a major constraint, either, given that some of the biggest scaling-up gains appear to have occurred in the post-World War II era.