This growth attracted the interest of Henry H. Porter, a Chicago railroad owner. He bought 25,000 acres (100 km²) of land further up the North Shore than Tower’s holdings around Two Harbors and Tower, an inland mining settlement named after its founder. Porter coerced Tower into selling the Minnesota Iron Company for 8.5 million dollars. He opened Chandler Mine, Pioneer Mine, Zenith Mine, Savoy Mine and Sibley Mine between 1889 and 1899. In 1896 the iron traveling through Two Harbors exceeded 2,000,000 tons. Two Harbors steadily built more docks and replaced the wooden docks with concrete over the course of the next several decades. Iron production continued steadily for many more decades; by the 1950s traditional iron mines had exhausted most of their resources. It had been known for many years that northern Minnesota had an ore called taconite, which could be refined into iron through a process called beneficiation. A taconite processing plant was built further north along the North Shore at Silver Bay, and it quickly became the major taconite shipping port. Minnesota taconite produces over half of the iron mined in Minnesota at the present date. Northern Minnesota is essentially covered with one large forest. Although the potential for a lumber industry was recognized early in the course of European settlement, the distances that it would have to be shipped made it uneconomical. But as eastern forests were logged out, the lumber industry moved into Wisconsin and Minnesota.. Lumber and forest products were shipped by rail from Duluth and Superior, Wisconsin to southern and eastern mills. Because of conservation efforts, many of the forests along the North Shore are now protected from deforestation, but there is still a strong paper industry that relies on pulpwood. In 1855 when a lock system first allowed steamboats onto the lake, eastern tourists began to travel onto Lake Superior for recreational purposes. They would then canoe or be ferried from Duluth up the North Shore and would stay in hunting and fishing camps. In the 1920s, the North Shore highway was built, which helped make the North Shore accessible by land. At the same time commercial fishermen began to go out of business as catches declined. Many of these fishermen built cabins and resorts, which were inhabited by more rich people on recreational trips. Certain exclusive clubs also bought land for resort and sport purposes. The Naniboujou Club Lodge was built to attract an exclusive clientele, and a group of Duluth businessmen, the Tettegouche Club, bought 9,346 acres (37.8 km²) of land for use as a private retreat.