LABOR DAY was originally intended to celebrate the condition of working people, and their contributions to the world. Today, it primarily signals the beginning of the school year, the calendar by which most American families live. It also marks the point at which the political campaigns get serious.

The tone of the congressional campaigns this year is very ordinary, so far -- and that, when you think of it, is curious. There are now nearly 11 million people out of work and, by the standards of American politics at any time between the 1930s and the mid-1970s, that would be the cause of outrage and vehement denunciation of everybody in office. Elections repeatedly turned on unemployment far lower than the present level. Perhaps the improvement in unemployment benefits has taken the edge off the American fear of being laid off.

Perhaps, more important, voters have lost faith in the federal government's ability to do much about it. That seems to be one of the lessons that people have drawn from the Carter administration. Under its policies, the economy generated jobs faster than ever before and yet in the last year and a half of its term unemployment was moving steadily upward -- along with inflation. If you really don't think that the government can do a great deal about the rate, and might make matters worse if it pressed too hard, then moral outrage isn't much help.

If you can't look reliably to the elections for a remedy, where do you look? That brings us to the other side of Labor Day, the opening of the schools. In college classrooms the number of adults is striking. In a tightening job market, school is not just for the kids. And for the kids, school is starchier than it once was. Ten or 15 years ago, when most people took it for granted that the jobs would be there, they asked whether children were having enough fun in school. Now the emphasis is back on performance. Parents' and teachers' sense of the world ahead for their children has changed.

This year is the centenary of the first Labor Day parade. You don't need to know much about the 19th century to appreciate the advances in working conditions and the security of working people. But perhaps that security is not quite so great as it might have seemed in January 1970 -- the last time that the unemployment rate was under 4 percent, then considered the standard of full employment. Compared with some in recent memory, the mood on this Labor Day seems to be slightly less trusting, slightly more cautious, and a good deal less confident about the relationship between election returns and unemployment rates.