 On May 31 , 1889 , the South Fork Dam collapsed upstream of Johnstown on the Little Conemaugh River . The resulting deluge devastated the city , killing 2 @,@ 209 people . As the city rebuilt , the Cambria Iron Company started work on a residential development atop Yoder Hill . To provide easy transportation up and down the steep slope for the residents of the new community of Westmont , the company decided to construct an inclined plane . In addition to being a convenient mode of transportation , the Johnstown Inclined Plane doubled as an escape route in case of another flood . <unk> was hired by Cambria Iron to design the incline . The rails used in the incline were all manufactured in Johnstown at Cambria Iron , with many of the tools needed in the construction also handcrafted there . The 232 @-@ foot ( 71 m ) Inclined Plane Bridge was built to span the <unk> River to provide access to the lower station of the incline . Originally named the Cambria Inclined Plane , the Johnstown Inclined Plane opened on June 1 , 1891 and cost $ 133 @,@ 296 to build . The convenience the incline provided stimulated a rapid growth of population in Westmont and made the borough one of the country 's first suburbs . Over 40 million trips were taken on the incline in its first 80 years of operation . 
