You have heard bad data. There was very few 30" gauge lines in USA, and far more at 36" gauge. In fact there were more miles of 42"or 24" ever, than 30" in the USA.
On June 25, 2002 I posted the list on NGDG of names of 8 of less than dozen such gauge companies in the USA and they total less than 34 miles. There is only one tourist RR of that gauge and it is in Montana.
The finest tourist line of this gauge is on the island of St. Kitts but is now reported too about to be abandoned.
Just consider your data source to be bad and never use it again.