As I have noted before, it’s sometimes hard to appreciate fully the energy industry’s size and scale. But a recent announcement by the operator of the Keystone pipeline system – which brings oil from Canada’s oil sands to refineries in the Midwest – is helpful in giving an insight into the importance of infrastructure in meeting America’s broad-based needs for energy.

Keystone operator TransCanada stated this week that the pipeline has delivered more than 1 billion barrels of crude oil since starting operations just half a decade ago.

That’s a lot of oil to move.

The CEO of TransCanada put the pipeline’s contributions in perspective, noting that it would take approximately 1.7 million train cars or 3.3 million trucks to transport that much oil.

For both the public and policymakers, it can be hard to understand how much oil this is.

One billion barrels is equivalent to all the proved crude oil reserves believed to lie underground in Oklahoma, one of the country’s largest oil-producing states.

And it’s about 40 percent more than ExxonMobil’s enormous Hebron project offshore of eastern Canada will produce over its three-decade lifetime.

So one billion barrels safely delivered makes a pretty compelling argument for approving the proposed Keystone XL expansion. Keystone XL would carry even more Canadian oil – as well as U.S. crude from North Dakota’s Bakken Shale – to refineries along the U.S. Gulf Coast. TransCanada submitted its initial application to the Obama administration for Keystone XL nearly seven years ago.

It is still waiting for an answer.

There are other arguments as well for approving Keystone XL, as I have noted in this space on numerous occasions. Some of these arguments come courtesy of the administration’s own State Department. Its own reviews show the project would have no adverse environmental effects, and would increase U.S. GDP by $3.4 billion.

The original Keystone pipeline is an economic engine for the regions it passes through, providing hundreds of millions of dollars in property taxes to counties, townships, and to school, fire, and natural resource districts.

Keystone XL would only enhance these economic benefits, while transporting crude oil in the safest manner possible.

This one-billion barrel milestone for the Keystone pipeline follows closely on the heels of another that marked five years of operations.

With such an impressive economic, environmental, and operational track record, it’s natural to ask: When is the United States going to start working toward similar milestones by approving Keystone XL?