The original east–west rail line in the area was built in 1855 by the Great Western Railway (GWR).

It connected Toronto to the east and Hamilton to the west, following the Lake Ontario shoreline, passing through the then-rural Parkdale area.

[1] From the west, the rail line climbed from the level of lakeshore up to Parkdale and then down again to enter the centre of Toronto.

Bridges over the new cut were constructed at Dufferin, Dunn, Jameson and Dowling streets to preserve access to the lake shore and Exhibition grounds.

West of Dowling Avenue, the new rail line bed was raised from the previous waterfront level to make an even elevation from the Humber River east to Sunnyside, providing subways at several points to provide grade-separated access to the waterfront from the north.