Everybody and their dog is going to link to this today, so there's probably not a whole lot of explanation needed. Musk's latest idea involves using rockets to transport passengers into the upper atmosphere and to land the rocket in a city on the other side of the planet.
Here's the thing: My grandparents began their lives riding horse and buggy to and from town. In the span of their lifetimes, transportation has evolved from horse and buggy, to auto, to airplane, and to space travel. Travel times in the early 1800s spanned from 1 day to get outside New York City to 5 weeks to get to Chicago. By the mid-1800s, you could travel from New York City to California in the same 5-week timespan.
I can imagine more than a few people will roll their eyes at Musk's latest dreamscape. But anyone who does is foolish. This idea won't take 100 years to come to fruition. I bet it'll be shorter than the 50 years needed to cut travel time across the United States.