Why the Seven New NFL Stadiums Being Built Are Mostly Domed

What it means here:The old stadium roofs were solid concrete that let no light through, so being inside felt like sitting in a giant parking garage. The new roofs are the opposite — sunlight filters right through them.

In general:Not letting light pass through; impossible to see through. The opposite of transparent (like clear glass).

What it means here:Several separate forces — concert money, Super Bowl rules, and television deals — are all coming together at the same time, and together they push teams to build roofs.

In general:To come together toward the same point, or to happen at the same time from different directions.

What it means here:Taxpayers now pay a smaller SHARE of each stadium's cost than they used to — yet they hand over more actual dollars than ever, because the stadiums have gotten so much more expensive. Two facts that seem to clash, both true.

In general:A statement or situation that seems to contradict itself, but turns out to be true anyway.

Here's a smart way to think about any expensive thing: don't ask "how much does it cost?" — ask "how much does it cost each time I use it?" A $100 pair of cleats you wear twice costs $50 per wear. A $100 pair you wear a hundred times costs $1 per wear. Same price tag, completely different deal.

Now look at an NFL stadium the same way. It costs around $3 billion, and the football team plays there only about 10 days a year. That's a gigantic machine sitting dark and empty 355 days out of 365 — a terrible cost per use. But put a roof on it, and suddenly it can host concerts, conventions, and big events all year long, in any weather. More days of use makes every single day cheaper. That — more than anything about football itself — is why almost every new stadium is getting a dome.

You can use this trick on your own money. Before buying something expensive, guess honestly how many times you'll really use it, then divide. It's how you tell a true bargain from a very fancy dust collector.

Suppose a new candy store opens near your school and you spend your $10 allowance there. Did your town just get $10 richer? No — that's $10 you now DIDN'T spend at the pizza place next door. Your money didn't grow; it just moved. Economists call this substitution: one kind of spending replacing another.

This is the secret to judging big promises like "a new stadium will boost the city's economy!" Most of the money families spend at a game is money they would have spent anyway — on movies, restaurants, or bowling — somewhere else in the same town. The stadium's cash registers fill up while other businesses' registers empty out a little, and the town as a whole barely changes. That's why economists who study stadiums keep finding that they don't create the boom that gets promised.

New wealth shows up only when the spending comes from OUTSIDE — visitors who wouldn't have come otherwise — or when something genuinely new gets made. So next time someone says a big project will "bring in money," ask the substitution question: is this new money, or old money in a new place?