 Most of the increase came in the coal mining districts, especially Glamorganshire, which grew from 71,000 in 1801 to 232,000 in 1851 and 1,122,000 in 1911.Part of this increase can be attributed to the demographic transition seen in most industrialising countries during the Industrial Revolution, as death rates dropped and birth rates remained steady.However, there was also large-scale migration into Wales during the Industrial Revolution.