| 1910 |
Henry L. Dougherty creates Cities Service Company to supply gas and electricity to small public utilities |
| 1911 |
Swiss Psychologist Carl Jung founds Analytic Psychology |
| 1909 |
Robert Peary reaches the North Pole |
| 1912 |
Cities Service first enters oil and natural gas business in the Mid-Continent Field with the purchase of the Quapaw Gas Company |
| 1912 |
Dougherty and the Cities Service Company buy the extensive oil and gas holdings of the Barnsdall Properties |
| 1912 |
British luxury liner Titanic, one of the largest ships in the world, strikes an iceberg and sinks with more than 1,500 lives lost. |
| 1913 |
Henry Ford begins to use standardized interchangeable parts and assembly-line techniques in his automobile-manufacturing plant. |
| 1913 |
Cities Service buys the Empire Gas Company. |
| 1914 |
World War I begins in Europe. |
| 1914 |
The Empire subsidiary of Cities Service discovers and develops the Augusta and Eldorado fields in Kansas. |
| 1915 |
Headquartered at 60 Wall Street in New York, Cities Service had 98 subsidiaries. |
| 1915 |
A German submarine sinks the passenger liner Lusitania, killing 1,198 people on board, including 128 American citizens. |
| 1916 |
Cities Service purchases its first refineries in Okmulgee, OK, Cushing, OK and Gainesville, TX. |
| 1916 |
Henry L. Dougherty, with fund-raising help from Josef Pulitzer, installs nighttime lighting for the Statue of Liberty in New York Harbor. |
| 1916 |
German-American theoretical physicist Albert Einstein publishes his General Theory of Relativity. |
| 1916 |
Cities Service acquires the Crew Levick Company and its refinery on Petty's Island in the Delaware River. To this day CITGO still operates a terminal on Petty's Island. |
| 1917 |
United States enters World War I. |
| 1917 |
Cities Service subsidiary Empire Gas & Fuel increases its fuel production from 3,000,000 barrels in 1915 to 36,000,000 in 1917. |
| 1918 |
Cities Service subsidiaries produce half the oil used by the Allies in the final year of the war. |
| 1918 |
World War I ends. |
| 1919 |
Cities Service has seven refineries as of November 28. |
| 1919 |
British aviators Arthur W. Brown and John W. Alcock make the first nonstop transatlantic flight. |
| 1919 |
Henry L. Dougherty uses motion pictures to convince business people to invest in Cities Service-the first such use of movies. |