OTHER RESOURCES OF MICHIGAN 105 



lished. There remained the problem of eliminating 

 impurities from the product — particularly bromine, 

 iron and gypsum, — and in 18G9, the State inspector- 

 ship of salt was created to promote greater purity 

 in the saline output. Seven years later, an associa- 

 tion of salt producers was organized to control the 

 marketing of the product, and by 1880 Michigan was 

 producing nearly half the salt of the country. Since 

 that time the State has continued to hold first place 

 in most of the years to the present time, occasionally 

 yielding the primacy to ISTew York. Although there 

 is some evidence of salt in the rocks of the Upper 

 Peninsula, the State's production has during this 

 period been confined to the southern peninsula. By 

 1890 salt was being produced in the counties of 

 Saginaw, Bay, Huron, St. Clair, Iosco, Midland, 

 Manistee, Mason and Gratiot. More recently Wayne 

 has taken first place, that county's production in 

 1916 amounting to 9,000,000 out of 16,000,000 bar- 

 rels produced in the State. This shows the shifting 

 of the major output from the Manistee-Ludington 

 area in the northwestern Lower Peninsula, which in 

 turn had taken the supremacy from the Saginaw 

 district. Indeed, the whole region fronting the St. 

 Clair and Detroit rivers overlying a deep layer of 

 rock salt, is now the most important salt territory 

 of Michigan, although important regions of rock salt 

 are likewise found underlying Manistee and Mason 

 counties in the northwest, and Alpena and Presque 

 Isle counties of the northeast. The Saginaw salt 

 has been obtained from a liriuo found at a depth of 



