Every four years, 40 to 50 million Americans vow that if their man doesn't win the presidency, they will move to Canada.

This year is no different, and I have heard many of my dearest friends say' "if Reagan is elected, I'm taking the family to Canada." Or, "If Carter gets in for another four years, I'm leaving the country."

The trouble with these threats is that the Canadians take them seriously. Since they are so short on population, the idea of 40 to 50 million new immigrants makes their mouths water.

The Canadians start building new homes and schools to accommodate the disenchanted American voters. Shopping centers are constructed, contracts are given out for drive-in theaters and motels.

The Canadians repaint all their buildings and touch up their lawns to make the Americans feel at home.

Night classes are given on how to treat the new arrivals. Welcome Wagons are beefed up, and new factories are built to provide jobs for the millions of Democrats or Republicans, who say they cannot live in the United States under a Communist Democratic or Fascist Republican regime.

To facilitate the move, Canadian customs officials are told not to open any luggage of American immigrants. Canadian mounties are instructed to go easy on traffic tickets. No expense is spared in preparing for the influx of people.

But what inevitably happens is that after the election the 40 or 50 million people who vowed they would go to Canada change their minds, and remain in the United States to stick it out under "That Man in the White House." i

I saw it happen when Nixon beat Hubert Humphrey, then when Nixon defeated McGovern, and again when Jimmy Carter Beat Ford.

Canada was waiting with welcome arms for all the people who said they couldn't live in the U.S. any more. "Nobody came.

All the hopes and dreams of the Canadians to double their population overnight vanished, but it left a taste of bitterness that lingers on.

The greatest cause of anti-American feeling in Canada can be attributed to the presidential election-year promises that people in this country have failed to keep.

How long can the Canadians keep building up their country for people who promise to go there, and then refuse to leave the U.S.?

At the moment Canada is in a terrible quandary. The ambassador in Washington has reported that 45 million Democrats have vowed to go to Canada if Ronald Reagan is elected president of the United States. He has also reported surveys indicate that 40 million Republicans will go if Jimmy Carter stays in the White House.

Canada must decide in the next few weeks whether to go through the motions of preparing for them for them or to ignore those vows as idle threats. Suppose this time all the people who say they're going to Canada really do? Yet suppose the Canadians spent all the money and nobody shows up?

It seems to me it is incumbent upon every American voter not to say he's going to Canada unless he really means it. If he is sincere about it, he should notify the Canadian immigration authorities.

I know it's hard to ask people at the height of an election campaign not to make threats they have no intention of keeping. All I'm suggesting is that if you want to tell someone you're leaving after the election, tell them you're going to France, where they don't care if you come or not.