Sunday marked the first anniversary of the derailment of a train carrying crude oil from the Bakken reserve area in North Dakota through the Quebec city. The disaster left more than 40 people dead.
Harper issued a statement to commemorate the loss of life and the damage to the city of Lac-Megantic.
"In the face of such a daunting challenge, it was essential for all levels of government to cooperate as closely as possible to assist the victims, the community and the local economy," he said Sunday. "One year later we can say that, while much remains to be done, our collective efforts are beginning to produce the desired results."
Canadian Transport Minister Lisa Raitt announced new regulations in April aimed at increasing safety on the Canadian rail system. The measure from regulator Transport Canada started with an order to remove around 5,000 tanker cars designated DOT-111 from service almost immediately.
Those types of cars were involved in the Lac-Megantic disaster and several others since the July 6, 2013 tragedy.
An accelerated rate of crude oil production in North America has strained existing pipeline capacity. Industry officials say rail transport is taking up the slack.