sentences:  At its southeast end, it junctions with the Berkshire Subdivision and Schodack Subdivision.After crossing the Hudson River on the Alfred H. Smith Memorial Bridge, it meets the River Subdivision and Port Subdivision at Selkirk and ends at Selkirk Yard, where the Selkirk Subdivision begins.The entire Castleton Subdivision was opened in 1924 by the Hudson River Connecting Railroad as part of a bypass around Albany.