Due to limited opportunities, between 1880 and 1910 there was extensive emigration, and around 300,000 Slovenes (i.e. 1 in 6) emigrated to other countries, mostly to the US, but also to South America (the main part to Argentina), Germany, Egypt, and to larger cities in Austria-Hungary, especially Vienna and Graz. The area of the United States with the highest concentration of Slovenian immigrants is Cleveland, Ohio. The other locations in the United States where many Slovenians settled were areas with substantial industrial and mining activities: Pittsburgh, Chicago, Pueblo, Butte, northern Minnesota, and the Salt Lake Valley. The men were important as workers in the mining industry, because of some of the skills they brought from Slovenia. Despite this emigration, the population of Slovenia increased significantly. Literacy was exceptionally high, at 80–90%.