Years ago on this blog I posted a link to a study of shipping lanes in the 18th and 19th centuries, Windjammer and East Indiaman Shipping Lanes. Now very little commercial cargo is shipped on sailing ships. Instead now there are container ships and air cargo. Weirdly there is a coincidence. Fed Ex according to Wiki shipped 15 million tonne kilometers in 2004. One clipper, The Blackadder, with a tonnage of 900 tons on a trip to Sydney was capable of shpping 20 million tonne kilometers in one 2 month voyage.
Here is a map of the air lanes of the world published as of 1944 from The Atlas of Global Geography. Link from Thande in Things that look like alternate history, but aren't at AH.com. Look at how Canada is nearly empty of air routes. And how the USSR has dense network of air routes compared to China, India and the Middle East.
Here is a map from 1920 about possible air lanes from The People's Atlas. This atlas was published so soon after WW1 with the result one of the only sections that is not prewar is this section. Helpfully it also has pictures of warplanes drawn to scale. As you can see the scale it presumes that commercial air travel was going to limp along at 100 miles per hour. What may please the those futurists who drew this map is that four airlines that were founded in 1920 still exist.
Here is an illustration of the air traffic in 2008 based on observed contrails. It is from a blog concerned with contrails, Contrail Science. The image below comes from a blog post about the growth of air travel in last 30 years, 30 Years of Airline Travel. The paper that blogpost is based on is not available.