The construction of the Keystone XL, a pipeline intended to bring hundreds of thousands of barrels a day of oil from Canada’s controversial oil sands to the United States, has been mired in delays as regulators assess its environmental impact, and activists and landowners protest what they see as one of the nation’s largest environmental threats.

But the attention surrounding the Keystone XL has mainly focused on its northern component, leaving its shorter southern stretch — which starts operating on Wednesday — and several other pipeline projects out of the limelight.

Wednesday is by no means the end of the Keystone and oil pipeline debate, but it marks a significant turning point as it takes oil companies one step closer to having a direct line from Alberta’s oil sands to refineries in Louisiana and Texas.

The southern Keystone runs from the huge underground oil storage tanks of Cushing, Okla. to oil refineries on the Gulf Coast. Other pipelines and rail services feed into it from the north. Once the Keystone pipeline’s north end is fully operational, it’s expected to move 830,000 barrels of crude oil per day, according to the Dallas Morning News.

The southern stretch of pipeline has generated its fair share of controversy. Several Texas landowners have filed lawsuits against the state for its use of eminent domain to claim land for the pipeline’s construction.

“They never had the right to take our land,” actress Daryl Hannah said in 2012, before getting arrested outside a construction site for part of the pipeline. “Were we to win, it would mean foreign companies like TransCanada don’t have the right to come in and take people’s land.”

Environmentalists also say the southern part of the Keystone XL, much like its northern counterpart, will contribute to an increased reliance on oil and gas in the U.S. for decades.

But unlike the northern section, the southern part doesn't link directly to Canada's oil sands. Extracting oil from Canada's vast oil sands is likely to help increase the country's carbon footprint by nearly 40 percent in 15 years. That is what made the Keystone's northern section so controversial, and what let the southern portion remain on the sidelines of debates.

But oil, including that from Canada’s oil sands, is still getting to and around the U.S., northern Keystone or not.

In the last few years, TransCanada, the owner of Keystone, along with several other pipeline companies, have won the right to build pipelines in the U.S. and across the Canadian border that will deliver just as much, if not more oil than Keystone’s northern section would.

Enbridge, TransCanada’s bigger rival, already has a pipeline that carries 450,000 barrels of oil a day from Alberta to Superior, Wis. Enbridge recently announced plans to nearly double the pipeline’s capacity to 800,000 barrels, which is virtually the same amount that would flow through Keystone’s northern section.

Both Enbridge and TransCanada also plan to spend a combined $68 billion on other pipelines throughout Canada and the U.S. in the next five years.

And as a workaround to the Keystone’s northern delays, oil companies are getting Canadian oil to the U.S. through other methods, mainly rail.

While environmentalists have long opposed a direct link between the oil sands and Gulf refineries, some of the oil being produced in Alberta is already getting there. It’s first going to Cushing, Okla., via rail. And, starting Wednesday, from there it can flow through the southern section of the Keystone XL to the Gulf.