Imagine what would have happened in 1937 had the builders of the Golden Gate Bridge stopped half-way across the water separating the San Francisco peninsula and San Marin County because a bunch of feuding politicians couldn’t agree to finish the job. Late-night comedians would still be making jokes about the giant diving boards into the Golden Gate strait. Two years ago this weekend, President Obama put himself in a similar position by endorsing construction of the southern leg of the proposed Keystone XL pipeline but delaying approval of the northern leg. Now it’s up to Obama to tell the builders to finish the job.

The Keystone pipeline would carry oil produced from Canadian tar sands south to America’s most advanced refineries on the Gulf Coast. These refineries are best-suited to refining the Canadian crude to satisfy the Environmental Protection Agency’s increasingly complicated gasoline-blend formulas that are intended to minimize emissions throughout the nation’s multiple climates and geographies.