What is the main idea of the passage?

Railways forced towns to give up local time and accept a shared standard (Each paragraph advances one claim: local time worked until railways made disagreement dangerous, so a shared standard spread.)

What happened in 1883, according to the passage?

Railroads in the United States and Canada divided the continent into standard zones (1840 is the British date; 1883 is the North American railroad decision, and the national law came 'decades later'.)

Why did differences in local time matter so little before railways?

Travel was slow, so small differences had no practical effect (The horseback traveller arrives 'long after such a difference had stopped mattering', which points at the speed of travel.)

In the last paragraph, 'imposed' means

established by force of authority or power (The industry set the standard for its own reasons and the public 'accepted it because the trains would not wait', so the standard was pressed on people, not offered.)

The Clocks The Trains Set: Level 4 Reading Comprehension Questions

For most of human history, noon was a local fact. A town set its clocks by the sun directly overhead, so a clock in one city ran several minutes ahead of a clock a hundred miles to the west. Nobody minded. A traveller on horseback arrived long after such a difference had stopped mattering.

Railways destroyed that tolerance. Trains ran on published timetables and shared single tracks, and a few minutes of disagreement between two stations was no longer an inconvenience but a collision. From 1840 British railway companies began keeping London time along their whole lines, printing it in their schedules and hanging it in their stations. Local time slowly gave way to what people called railway time.

The same pressure produced the same answer elsewhere. In 1883 the railroads of the United States and Canada divided the continent into standard zones and reset their clocks on a single day. Cities followed the railroads rather than the other way round; national law caught up decades later.

It is worth noticing who decided. No parliament designed modern time. A private industry needed its network to agree, imposed a standard because coordination was cheaper than accidents, and the public accepted it because the trains would not wait.

Comprehension questions