The world today is very neatly divided into 24 efficient, well-ordered time zones that correspond with the 24 hours in a day. If it’s 2 p.m. in Philadelphia, it’s 11 a.m. in Los Angeles, 7 p.m. in London, 8 p.m. in Paris, 9 p.m. in Tel Aviv, and 4 a.m. tomorrow in Seoul.

Time is uniform, but it wasn’t always so. Standardization didn’t begin to emerge until the late 19th century.

In her new book “The Global Transformation of Time 1870–1950,” Vanessa Ogle, the Julie and Martin Franklin Assistant Professor of History in the School of Arts & Sciences, recounts the nearly century-long effort to homogenize clocks around the world, and the difficulties supporters faced in forming international standards.

Ogle says the initial push for uniform time originated in Europe and the United States in the late 19th century. Onlookers saw a world that bore some resemblance to 21st century globalization, and spoke of the ways in which time was accelerating and distance was becoming less important in light of new means of communication and transportation, such as the steamship, railway, and telegraph.

“They came to conclude that the world in a way was shrinking, not unlike today’s notion of the global village,” Ogle says. Advocates for uniformity believed a standardized system of time would act as a “kind of lubricant for this globalizing world, and would facilitate the flow of goods, people, and ideas.”

The British Empire, which was expanding along with other European empires during this period, foresaw standardized time as a tool to synchronize its vast overseas possessions, ease the spread of information and transportation, and help maintain control.

In the early 1900s, the Empire tried to introduce Greenwich Mean Time—set by the Royal Observatory in Greenwich, London, which lies on the Prime Meridian—in British India, but was greeted by a resistance movement that Ogle says overlapped with an early Indian nationalist movement.

“In other parts of the British Empire, the British were even less successful,” Ogle says, “precisely because of the logistical challenges and difficulties involved with getting people to observe the new times.”

Promoters of uniform time also called for the adoption of the Gregorian calendar as the universal calendar, which would replace the numerous religious and cultural calendars used throughout the world.

Ogle says convincing people to adopt the Gregorian calendar was more controversial than any talk of standardizing time. She says there was pushback from religious groups, such as Adventist Christians, Muslims, and Jews, who protested because the universal calendar would have abolished their Sabbath.

“Ultimately, that led governments to be too cautious about pushing something like this through,” Ogle says.

The calendar reform movement petered out in the 1930s and ’40s. The move to standardize time failed, too—up until the Second World War.

Ogle says the standardizing and globalizing impact of World War II, coupled with U.S. occupations in East Asia and other parts of the globe, and the advent of the jet age and increasing military and commercial aviation, ultimately led to the triumph of uniform time.

For the most part, the West got what it wanted. Standard time was adopted internationally based on Greenwich Mean Time (GMT). The East Coast of the United States is at GMT -5, or five hours behind the Royal Observatory.

The standardized calendar enthusiasts found some success as well. Ogle says imperialism, colonialism, and trade have caused many parts of the world to use the Gregorian calendar alongside their cultural or religious calendars.

Time is set, but there are some renegades in the international system. For reasons of nationalism, China, which is fairly equal in size to the United States, has only one time zone for the entire country when Ogle says it should have three or four.

The once British India, now a booming republic, is five-and-a-half hours from Greenwich Mean Time, or GMT +5:30, defying its former invader still.

In August, North Korea adopted its own time zone, GMT +8:30. It previously observed GMT +9, the same as Japan and a remnant of Japanese imperialism.

“Time for all, you could say, it’s just a convention,” Ogle says. “But it has these very symbolic, charged qualities to it that make it a little more than just some technical convention.”