Thank God Willis Haviland Carrier invented air conditioning — for the most part.

Before air conditioning, the heat drove us outside and brought us together. Friends sought the shade of trees or a refreshing dip in a lake or river.

On the hottest nights, whole families brought their blankets and pillows to riverbanks, where it was cool.

In the evening, neighbors sat on their large front porches, enjoying a cool breeze as they sipped lemonade and told stories.

Even in the 1970s, when I was a kid in the suburbs of Pittsburgh, few homes had air conditioning. Our windows were always open.

At night you could hear neighbors talking, a distant baby crying and Pirates’ announcer Bob Prince calling a game on somebody’s porch radio: “… he missed it by a gnat’s eyelash!”

In the mornings, I’d wake early to the sound of chirping birds. I could smell the cool dew outside my window and the scent of toast and scrambled eggs my father was cooking up in the kitchen.

Air conditioning has certainly changed many things for the better — I’m nice and cool as I write this column — but it has brought with it some downsides.

Most neighborhoods are sealed shut now. Rather than the voices of children playing, all you hear is the hum of air conditioning motors.

My Uncle Jack’s 1920s home was designed with high ceilings, cross ventilation and large hallways to dissipate heat — magnificent features that are no longer necessary in today’s low-ceilinged suburban houses that put the porch in the back and the garage in the front.

No lemonade for you!

Commercial buildings used to have windows that opened, but that isn’t necessary anymore.

Today’s glass-plated buildings are designed to keep the light and air out, making us oblivious to whatever season it may be.

Before Congress got air conditioning in the 1920s, hot, humid Washington was empty from mid-June to September.

Now the Congress can spend lots more time working on — as the great New York Times columnist Russell Baker once put it — “… the promulgation of more laws, the depredations of lobbyists, the hatching of new schemes for Federal expansion and, of course, the cost of maintaining a government running at full blast.”

Sure, air conditioning has dramatically improved life for the elderly and others with respiratory problems. It’s saved a lot of lives. And our productivity has been vastly improved by the cool air.

I’m just saying that sometimes it’s good to be hot, sweaty and uncomfortable.

When I lived in the D.C. area in 2004, a group of us sat next to the Capitol Building in 102 degree heat during a Fourth of July ceremony.

Thousands of people were jammed together dripping with sweat, but nobody really minded.

We sang the National Anthem together and it was a moving event. We watched the fireworks go off above the Washington Monument. It was a spectacular experience to be together in the heat with so many others.

But as soon as the last of the fireworks exploded, most people fled to their air-conditioned cars and homes and went quickly back into isolation.

I didn’t.

I put my car windows down. We drove slowly through the streets of Washington, listening to the occasional firecracker and people talking as children played with sparklers.

Of course, as soon as I got to my Virginia condo, I cranked the AC as high as it would go — happily enjoying the incredible upside of Willis Carrier’s cool invention.

See Tom Purcell’s syndicated column, humor books and funny videos featuring his dog, Thurber, at TomPurcell.com.