HENRY BOTHIN MAAS

This lovely illustration by Henry Maas is of a DC-3 flying over Treasure Island during the Golden Gate International Exposition. The Douglas DC-3 is:

...an American fixed-wing, propeller-driven aircraft whose speed and range revolutionized air transport in the 1930s and 1940s. Because of its lasting impact on the airline industry and World War II it is generally regarded as one of the most significant transport aircraft ever made. (SOURCE: Wikipedia)

If you took any commercial flights back in the 1950s I'd say you most likely flew on a DC-3.

Click on image to see it larger.

As to the Exposition seen below the flight over Treasure Island: 

The Golden Gate International Exposition (1939 and 1940), held at San Francisco, California's Treasure Island, was a World's Fair that celebrated, among other things, the city's two newly-built bridges. The San Francisco – Oakland Bay Bridge was dedicated in 1936 and the Golden Gate Bridge was dedicated in 1937. The exposition was opened initially from February 18, 1939 through October 29, 1939. It opened again from May 25, 1940 through September 29, 1940. (SOURCE: Wikipedia)

My father has fond memories of going to the Exposition and in fact the island was later converted to military use and was where he retired from the Navy. His office was in one of the original Exposition buildings which today is a museum.

As to the illustrator, Henry Bothin Mass, unfortunately I've found little about him. He was born in Wisconsin on November 4, 1903 and resided in San Francisco from 1924-1940. He later moved to Walnut Creek, California. He died September 22, 1994. (SOURCE: Edan Hughes, Artists in California, 1786-1940.)

The Standard Oil Bulletin was published, I believe, monthly for stockholders. If you do a little bit of googling you'll find a lot of beautifully illustrated covers done by various illustrators. I wish there was more information about Mr. Mass. I'd love to see more of his work.