the curious Carillon and Grenville Railway, Québec

Actually in Canada, rather than America.

The Carillon and Grenville Railway operated for 56 years between its namesake towns on the Quebec side of the Ottawa River. It was a portage railway with no outside railway connections so its owners had no need to modernize. When it ceased operation in 1910 it was a living museum with most of the original 1854 equipment still running on the original “U” rails. The rails were still 5’6” (1,676 mm) apart as the original builders intended, making the railway Canada’s “Last Broad Gauge.”  read the rest here