The coming of railroads in 1870 opened the possibility of the development of other industries in this territory. Within the same year the Milwaukee and Northern Railroad which ran through the central part of the county and the Milwaukee, Manitowoc, and Green Bay Railroad which was to go through the eastern section, were given charters to build and operate railroad lines.

The improvement of the harbor at Port Washington in the year 1870 also aided greatly in the exporting of farm and industrial products and in the importing of essential goods needed throughout Ozaukee County.

The timber which was cut during land clearing operations was cut up in the many sawmills and was used to build homes and barns, for railroad ties, and in cooper shops which built barrels and made shake shingles.

Other natural resources which developed local industries were Niagara limestone and a high quality clay and sand used in the manufacture of building materials such as brick and tile. The most prominent of the quarries which were operated were the Lake Shore Quarry near Lake Church, Drucker Quarry near Port Washington and Groths at Cedarburg and Grafton.

All of the old mills and large structures as well as small homes, schools, and churches were built of this native limestone. Probably the most prominent of such structures are the County Courthouse and St. Mary's Church at Port Washington.