A fatal explosion caused the closure of the last of four pipes.
Oil began flowing through Enbridge Energy Partners' Line 3 near Clearbrook early Monday, officials said in a news release. Three other lines that had initially been shut down because of the explosion had restarted Thursday.
Enbridge said workers repaired Line 3 over the weekend, replacing a segment of pipeline about 180 feet (55 meters) long. Workers also continued to clean up the site after about 325 barrels of oil were released during the incident, the company said.
Oil-soaked soil was taken off site, and the company said it will continue working with the U.S. Environmental Protection Agency and the Minnesota Pollution Control Agency to finish environmental cleanup.
The results of the ongoing investigation into the cause of the explosion weren't expected for several weeks.
Two welders were killed Nov. 28 when something ignited leaking fumes and oil from the pipeline. Steve Arnovich, 35, and Dave Mussatti Jr., 37, were part of a 19-member crew repairing a pipe section where a pinhole leak had been found previously.
The pipeline carries roughly 16 percent of U.S. crude imports from Saskatchewan through Minnesota to the Chicago area. Initial reports of the fire caused a brief spike in oil prices until it become clear the pipeline would quickly resume pumping.