Roger N. Anderson works as a senior research scientist at the Center for Computational Learning Systems at Columbia University. The views expressed in this commentary are his own.

(CNN) Hurricane Irma took a dramatic toll on Florida's electric grid, with as many as 15 million people losing power. It struck almost 16 years after 9/11, when New York's power grid was adversely affected by the horrific terrorist attacks.

It's worth examining the differences between restoring electric power to Lower Manhattan after 9/11, which took a matter of days , and the forecast for the restoration of power to Florida, which could take close to two weeks -- at least for the western parts of the state.

There is a critical distinction between the New York City power grid and that of much of Florida. The New York City grid is mostly underground -- 93,000 miles , or 75% of the total grid. That is enough cable to wrap around the Earth 3.6 times. However, Florida's power grid is largely above ground, 60% in fact , and much of the grid damage was the result of wind gusts toppling trees and power lines strung across poles.

When all the electric power was knocked out to the underground power system in Lower Manhattan on 9/11, Con Edison laid temporary power cables on street curbs that first day, as they repaired the underground damage within the critical 72 hour window after which food and drink from refrigerators and freezers goes bad. People tend to panic after that.

Restoring power to Florida will be more difficult. It's not just that the overhead poles were damaged or destroyed, but also the overhead connections between the pole-bound transformers and heavily damaged homes and businesses were damaged as well.

Given the threat posed by putting power lines above ground, why not put power to all critical infrastructure in the United States (not just Florida) underground? While we cannot prevent every blackout, we can certainly speed up repair time and better deal with inclement weather (and terrorism) by putting these wires underground. It's worth noting that we keep much of our critical infrastructure underground already -- including pipelines, water, sewage, and natural gas lines.

The standard utility answer is that it costs too much and takes too much time to dig the trenches to bury the electric distribution feeders in the streets and make the necessary underground lower voltage connections to each house, apartment building and business.

As regulated public utilities, almost all power companies in the US are "cost-plus-a-few-percent-profit" operations. In other words, utilities profit from restoring overhead power lines after each hurricane. They are allowed to increase customer bills to recover not only the cost of the repairs, but also the few percent profit as well.

Utility companies from across the United States are rushing to Florida to help local companies get their power and their overhead poles back up as fast as possible. It is a community-supporting activity that is arduous and dangerous.

Follow CNN Opinion Join us on Twitter and Facebook

But did you ever wonder why power companies put the replacement poles in the exact same positions that the destroyed poles were occupying? That restoration activity preserves the status quo until the next hurricane knocks down the new poles, and the cycle repeats, over and over again, across the US.

Now utility companies genuinely want to help their neighboring companies, but doing so poses a risk to national security. Underground power systems are significantly harder to attack or knock out than overhead systems.

Given that reality, and the fact that climate change promises more and more violent weather disruptions, we should immediately move to put all power distribution systems underground. While a national infrastructure project like this might cost more than a wall with Mexico, it's much more critical to our safety and security in the long term.