Back when FedEx started in the early 1970's, the gooberment strictly regulated who could operate passenger and freight airlines. But, there was a loophole that small aircraft were not regulated. FedEx used Dassault Falcon business jets to get around the regulation. Sometimes, large cities would have a squadron of FedEx Falcons fly in one right after the other.

Fred Smith was working on his MBA and wrote a paper that ended up being the business plan for FedEx. He got a lousy grade on the paper. Years later, he was back there (probably to dedicate a building he donated to the university), and he walked up to the professor's office. The door was closed, but he could see that that the lights were on in the office. He was going to day rub the guy's nose in it, but instead walked away.

FedEx almost went bankrupt early on. A lot of his pilots would fly for free to keep the company afloat. When things stabilized and FedEx started buying big jets (after deregulation), and took care of those "kids" who worked for free to save the company. There were a lot of 20-something year old widebody captains at FedEx.

FedEx almost lost their ass again with Zap Mail, essentially fax machines linked by satellite dishes. The documents would be scanned and printed at FedEx offices, and delivered by FedEx trucks.

The early FedEx model was a spokes-and-hub. They eventually added more hubs, but the idea was pretty much the same. But, vast increases in efficiency came with true networks, where a package could have multiple paths to get where it was going. The trick was to keep every path between network nodes operating at or near full capacity. When traffic on one link in a path hit 100%, packages would be routed through less direct paths that still had unused capacity. Sometimes a package staying in Texas flies to Memphis first, sometimes it goes from one Texas city to another by truck.

Southwest Airlines uses a network instead of spokes-and-hubs. On my frequent flights from Bubbaville, FL to Norfolk, VA back in 2010-2011, I'd go through Orlando, Baltimore, Memphis, Chicago, or Houston, without any apparent rhyme or reason.

A lot of FedEx's and UPS Air's business is two-day air freight. They fly every plane they have at night to cover the next-day freight, and then fly their most efficient planes in the daytime to get the two-day freight moved.