I'm William Brangham, and this is Horizons.

Sports betting is exploding across the U.S.

In just a few years, what once was illegal everywhere

but Nevada has now become a nationwide $150 billion industry.

With every bet now just one click away,

we look at how online gambling is changing our brains and behavior. Coming up next.

Welcome to Horizons from PBS News.

The Super Bowl is this weekend, and it is hard to avoid the avalanche of ads for sports betting apps,

like Draft Kings or FanDuel, all offering to ratchet up the fun and deliver big rewards.

One more catch. One more catch, one more yard, one more yard.

No more yards, no more yards.

Ahead of the big game, a slew of celebrities are urging us to put our own money on the line.

It's time to bet on something new.

Football players, I'm making my bet on who's going to win.

And you can bet with me or against me.

Americans are expected to place a record-breaking $1.7 billion in legal bets on just the Super Bowl. This is a massive shift in a very short period of time.

In 2018, the U.S. Supreme Court struck down the federal ban on sports betting.

Now, 39 states, D.C. and Puerto Rico allow it.

And the floodgates have opened.

Americans are betting an estimated $150 billion a year

on sports. So with a full-bore casino potentially inside every phone, a rising chorus of experts

who study problem gambling and addiction are ringing the alarms. For more on how this is

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