With the U.S. unemployment rate at a still agonizing and unacceptable 7%+, Americans are understandably concerned about anything that might cause an additional loss of jobs.

And one of the favorite targets for employment blame--popular on both sides of the political aisle--is robots. Robots and other automation technologies, it is said, are "stealing our jobs." Robots now build things people used to make. Computers now store, process, and analyze information that used to be handled by people. And so on...

Related: Robots on the Rise: Is Your Job at Risk?

If we don't stop this relentless technological "progress," the story goes, we will soon automate our entire society and put ourselves out of work.

Don't bet on it.

And, at least from a high level, don't worry about it.

Although it obviously will come as little consolation to those whose jobs are threatened or eliminated by technology, this economic transformation process has been going on for centuries, and the vast majority of Americans still have jobs.

As recently as 200 years ago, most Americans worked on farms. During the 19th Century, as the Industrial Revolution really got cranking, workers moved off farms and into manufacturing. And in the second half of the 20th Century, as manufacturing became more automated, and many manufacturing jobs shifted offshore to take advantage of cheap international labor, the majority of workers in the U.S. economy shifted to the services sector.

This economic process, which has been described as "creative destruction," can be painful and tumultuous, but it produces a vibrant and dynamic economy. It has helped the U.S. become the richest country in the world. And it is the reason why, even after two centuries of jobs lost through automation and productivity gains, almost 150 million Americans have jobs--most of which didn't even exist in the age when most people were working on farms.

As an example of how professions and industries can shrink while overall employment grows, take a look at this chart from the U.S. Census Bureau. The chart compares U.S. employment in 1940 and 2010:

The first thing to notice is that, despite the number of jobs that have been destroyed by technology over the past 70 years, the number of employed Americans has tripled over this period, from 45 million in 1940 to 139 million in 2010.

The second thing to notice is that America's biggest industry in 2010 is a combination of educational services, health care, and social assistance--an industry that now employs nearly a quarter of the working population--barely registered in 1940. Back then, the biggest industry was manufacturing, which employed a similar percentage of the country.