Only four navigable passes pierce the barrier range of the Appalachian Mountains in the United States , and the rivers headwaters begin on the western side of Tunnelhill , PA in northern Cambria County , Pennsylvania starting in Cresson Pass transited by the line of the Eastern Continental drainage divide . The river 's upper valley falls off gradually enough for the terrain to form a natural transportation corridor , one navigable by muscle powered vehicles such as Indian travois and Conestoga Wagons . Consequently , when settlers pushed west from the Susquehanna basin , the waters falling or rising in the eastern side of the drainage divide , ran down through valleys Amerindians had used to travel to the connect the west to the east for centuries . When Pennsylvania made a bid to connect to the business opportunities its leaders saw in the new settlements growing rapidly in the Ohio Valley they launched the great engineering project of the Pennsylvania Canal System which connected through the valley to Johnstown , PA The river was paralleled by the western inclines of the Allegheny Portage Railroad , connecting the two branches of Pennsylvania Main Line Canals , with the western terminus of the portage railroad at Johnstown . Created as part of the Pennsylvania Main Line of Public Works the Railway operated from its completion in 1834 until it was sold in 1854 to the Pennsylvania Railroad , which took over its right of ways . Thereafter , the rivers banks have hosted one of the most important rail transport corridors running east – west across the Appalachian Mountains On May 31 , 1889 , a dam on the South Fork holding back a slightly longer than 2 mile reservoir failed , sending a wall of water down the Little Conemaugh at 40 mph ( 64 km/h ) and up to 60 ft ( 18 m ) high , resulting in the loss of 2,209 lives in the worst civilian disaster of the 19th century in the United States . The event is remembered to history as the Johnstown Flood
Johnstown Flood
Johnstown Flood
Little Conemaugh River