A free trade treaty, eliminating tariffs and reducing other barriers between the U.S. and Canada, has run into a roadblock. Signed by President Reagan and Prime Minister Brian Mulroney last January, and passed overwhelmingly in the House of Commons this week, it is being held up in the unelected Senate.

The Canadian Senate is much like the House of Lords in the British Parliament, with members appointed for life. It has no power to kill the trade measure, but it can delay it until Mulroney calls for national elections. The trade bill would be the main issue in such elections.In a significant sense, the opposition to the treaty is not so much about trade as it is about what it means to be a Canadian. Canadians have these periodic bouts of identity crisis over living so close to the U.S., or having French as one of their national languages.

The trade bill would open the Canadian border to U.S. goods and services, eliminate the $2 billion a year Canadian businesses and consumers pay as tariffs on imported U.S. goods, and make the American market even more available to Canadian products.

In sum, the bill would more closely integrate the economies of the two countries and the $150 billion a year in business they do with each other.

That is precisely why some Canadians oppose it. They claim their country already is losing its culture and identity to the larger U.S. presence that tends to overwhelm all things Canadian. Books, movies, magazines, TV shows, autos, music, consumer products of every kind, tend to be American. Some fiercely oppose this Americanization of Canada.

But such xenophobic attitudes should not be allowed to prevail. The trade treaty - largely begun at the urging of Canada - will be good for both nations. Free trade is the best option. Lower prices and greater employment should result on both sides of the border.