I respectfully disagree with the above response. The loss of jobs for saddle and carriage makers was overwhelmingly outpaced by the creation of new jobs created by the invention of the automobile. By 1920, more than eight million new automobiles were on American roads, largely because of Henry Ford's efforts at assembly line production and his belief that every American family should own an automobile. Production of steel, glass, rubber and textiles used in the production of automobiles increased exponentially. Additionally, the production of oil to fuel these automobiles and construction of new roads added thousands of jobs to American payrolls. Few innovations have created more jobs and had a greater influence on American prosperity than the automobile. It not only created jobs in its manufacture, it allowed Americans to live away from their work outside city limits, and thus led to the construction of a new phenomena, the suburb. This alone led to thousands of jobs in construction, plumbing, electrical work, etc. To compare jobs gained by automobile construction to the loss of jobs in the horse and carriage industry is similar to comparing the loss of jobs manufacturing bows and arrows to the gain for modern armaments. The phrase "horse and buggy" is used to describe aniquated methods not without good reason.
When automobiles first came to be manufactured on a large scale, they destroyed some jobs, but created many others. On the whole, they led to the creation of more jobs than they destroyed.
Think about all the jobs that were no longer necessary once automobiles took over. There was no longer nearly as much need for stable workers and farriers. There was much less need for harness makers and carriage makers. All of these sorts of jobs were destroyed by cars.
On the other hand, think of all the new kinds of jobs that came into existence. There was a need for people to make the cars, of course. But there was also a need for people to extract and refine oil. There was a need for gas stations. There was a need for people to build roads for the automobiles to drive on. All of these sorts of jobs were created, making up for the jobs destroyed by the reduced use of horses.
I think you misunderstood what pohnei397. He/she clearly states that "on the whole, they led to the creation of more jobs than they destroyed." So pohnei397 and larrygates are essentially saying the same thing; however, larrygates gives a lot of useful details in his answer.