Castlereagh River
The Castlereagh rises 20 km west of Coonabarabran in the heart of the Warrumbungle mountains at an elevation of about 850 metres. From its commencement upstream in the mountains the river initially flows east through the town of Coonabarabran. It then arcs round south and southwesterly to the village of Ulamambri, then south to Binnaway, and SSW to the small town of Mendooran which lies at the eastern side of the river's hook-shape. From here the Castlereagh flows in a westerly direction at the flattened bottom of the hook and then turns north-westerly towards the town of Gilgandra. From Gilgandra it continues to run northwesterly across the plains through Gulargambone and Coonamble, then continuing across expansive plains, with no urban centres, where elevations are less than 200m, until it joins the Macquarie River at its uppermost reaches beyond the Macquarie Marshes. Its confluence with the Macquarie is about 65 km SW of Walgett. Not far from the Castlereagh/Macquarie confluence the Macquarie itself joins the Barwon River at a place about halfway between Walgett and Brewarrina.
Little Conemaugh River
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