20th Century
In 1918, the Canal was replaced by the larger New York State Barge Canal. This new canal replaced much of the original route, leaving many abandoned sections (most notably between Syracuse and Rome). New digging and flood control technologies allowed engineers to canalize rivers that the original canal sought to avoid, such as the Mohawk, Seneca, and Clyde rivers, and Oneida Lake. In sections which did not consist of canalized rivers (particularly between Rochester and Buffalo), the original Erie Canal channel was enlarged to 120 feet (37 m) wide and 12 feet (3.7 m) deep. The expansion allowed barges up to 2,000 short tons (1,800 t) to use the Canal. This expensive project was politically unpopular in parts of the state not served by the canal, and failed to save it from becoming obsolete.
The new alignment began on the Hudson River at the border between Cohoes and Waterford, where it ran northwest with five locks, running into the Mohawk east of Crescent. While the old Canal ran next to the Mohawk all the way to Rome, the new canal ran through the river, straightened or widened where necessary. At Ilion, the new canal left the river for good, but continued to run on a new alignment parallel to both the river and the old canal to Rome. From Rome, the new route continued almost due west, merging with Fish Creek just east of its entry into Oneida Lake.
From Oneida Lake, the new canal ran west along the Oneida River, with cutoffs to shorten the route. At Three Rivers the Oneida River turns northwest, and was deepened for the Oswego Canal to Lake Ontario. The new Erie Canal turned south there along the Seneca River, which turns west near Syracuse and continues west to a point in the Montezuma Marsh (43°00′11″N 76°43′52″W / 43.00296°N 76.73115°W / 43.00296; -76.73115). There the Cayuga and Seneca Canal continued south with the Seneca River, and the new Erie Canal again ran parallel to the old Canal along the bottom of the Niagara Escarpment, in some places running along the Clyde River, and in some places replacing the old Canal. At Pittsford, southeast of Rochester, the Canal turned west to run around the south side of Rochester, rather than through downtown. The Canal currently crosses the Genesee River at the Genesee Valley Park (43°07′17″N 77°38′33″W / 43.1215°N 77.6425°W / 43.1215; -77.6425), then rejoins the old path near North Gates.
From there it was again roughly an upgrade to the original canal, running west to Lockport. This reach of 64.2 miles from Henrietta to Lockport is called "the 60‑mile level" since there are no locks and the water level rises only two feet over the entire segment. Diversions from and to adjacent natural streams along the way are used to maintain the canal's level. It runs southwest to Tonawanda, where the new alignment discharges into the Niagara River, which is navigable upstream to the New York Barge Canal's Black Rock Lock and thence to the Canal's original "Western Terminus" at Buffalo's Inner Harbor.
The growth of railroads and highways across the state, and the opening of the Saint Lawrence Seaway, caused commercial traffic on the canal to decline dramatically during the second half of the 20th century.
Read more about this topic: Erie Canal