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Roman influence -

The imperial system as it is known today was developed from early British units of measurement, which were heavily influenced by the Romans and the Latin language. Units like the "foot" (pes, in Latin) and the "ounce" (uncia) laid the foundation for later measurement systems.

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Anglo-Saxon measurements -

After the fall of the Roman Empire, the Anglo-Saxons developed their own units of measurement. This included the "yard" (believed to have been based on the average length of a man's belt, known then as a girdle) and the "acre" (an area that could be plowed by one man with an ox in a day).

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Yard and pound -

During the 12th century, the yard and pound were standardized. The measurement for a yard was established as the distance from the nose to the thumb of King Henry I, and the pound was based on the weight of 48 barley-corn grains.

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Magna Carta -

In the year 1215, a royal charter known as the Magna Carta was signed by King John of England. The charter included clauses that aimed to standardize measures of wine, ale, corn, and cloth across the realm so as to prevent fraud and ensure fair trade. These measurements continued to be in use even as the British Kingdom established the American colony in the early 1600s.

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Birth of the imperial system -

The Weights and Measures Act of 1824 was established by British Parliament as a way of standardizing and consolidating various measurements into a unified system. This is formally considered to be the point at which the imperial system was born.

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Industrial Revolution - The imperial system helped to establish a standard measurement across all areas of manufacturing and industry, which is said to be one of the main causes of the Industrial Revolution in the 18th and 19th centuries.

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Revolutionary War -

After gaining independence in 1776, the United States continued to use the familiar British system rather than adopt a new one. This is because changing to a new system would have been costly and incredibly complex.

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Thomas Jefferson -

As Secretary of State, Thomas Jefferson (1743–1826) proposed a decimal-based measurement system to Congress in 1790. He envisioned a more rational and universal system, but Congress did not adopt his proposal.

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Industrial growth -

Even though the imperial system was widely in use, it wasn’t until the industrial expansion in the 19th century that the system was deeply entrenched in American manufacturing, construction, and commerce. After this, changing America’s system of measurement would be virtually impossible.

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Metric Act of 1866 -

The Metric Act of 1866 legally permitted the use of the metric system in the United States, with the aim to facilitate international trade. The act allowed the use of the metric system in the US, but it wasn’t mandatory. Indeed, both systems were used in confusing ways, but people still favored the imperial system for everyday purposes.

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Treaty of the Metre -

Also known as the Metre Convention, this treaty was signed by the US and other nations in 1875. It established the International Bureau of Weights and Measures (BIPM), an organization that promotes standard units of measurement in the international community to this day.

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National Institute of Standards and Technology (NIST) -

Formerly known as the National Bureau of Standards, the NIST was established in 1901 to be responsible for maintaining uniform measurement standards in the US. But there was one major problem: the country still supported both imperial and metric systems.

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Metric study -

In 1968, the US Congress commissioned a study to explore the benefits and feasibility of switching to the metric system. Afterwards, the Metric Conversion Act was signed in 1975, which declared metrication as the preferred system for US trade and commerce. But the transition was voluntary and lacked the enforcement needed for a nationwide shift.

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United States Metric Board (USMB) -

The USMB (logo pictured) was established in 1975 to plan and coordinate the metrication process, but it faced strong opposition and had limited power to enforce changes, leading to slow and fragmented progress and ultimately the agency’s dissolution in 1982.

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Cost concerns -

Businesses, particularly small- and medium-sized enterprises, were concerned about the financial burden of converting machinery, packaging, and processes to the metric system.

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Dual-labeling -

Many products and road signs began to feature both metric and imperial units, which allowed for some metric familiarity. But this endeavor still predominantly maintained the status quo and did not necessitate a full switch.

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International trade -

Global trade agreements sometimes required metric labeling, especially when companies shipped goods internationally. This led to an increase in the use of metric units in international contexts, but it did not significantly alter domestic practices in the US.

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Interstate commerce -

Since most US states had established a consistency in commerce and infrastructure, communications between states continued to use the imperial system to avoid confusion and ensure smooth operations. This practice further disregarded the metric system as a possible alternative.

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Mars Climate Orbiter -

In 1998, NASA launched the Mars Climate Orbiter in the hopes that it would navigate around Mars and study the planet’s atmosphere. But a year later, hopes were dashed as a result of an inaccurate conversion between imperial measurements and metric measurements.

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Mars Climate Orbiter -

The robotic space probe was lost because its navigation software was using imperial units while the team on Earth was using metric units. This discrepancy led to the miscalculation of the spacecraft's flight path, causing it to either burn up in the Martian atmosphere or skip into space.

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Apathy and economy -

The only question that remains is why, after all this time, the US has still not switched to the metric system. The truth is that the general public still shows very little enthusiasm for metrication. There are also high costs associated with converting industries, transportation systems, and consumer goods to the metric system.

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Cultural identity -

The imperial system has become intertwined with American identity and tradition, with many viewing it as part of the national heritage and worth preserving. This is further supported by the fact that the US is one of only three countries to use the imperial system, alongside Liberia and Myanmar.

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Complex transition -

The process and costs required to change road signs, construction standards, and educational materials are sometimes considered to be insurmountable. Many bureaucratic entities have cited these significant logistical challenges as reasons to avoid converting to the metric system.

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Incremental adoption -

Some industries, such as pharmaceuticals and electronics, have adopted metric measures due to international standards, but this adoption has not been universal across all sectors.

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Public resistance -

Many Americans are resistant to the metric system, finding it foreign and unnecessary, particularly given the extensive reeducation and adjustment required. Indeed, the imperial system has been deeply integrated into American society, and the thought of switching to another system seems unnecessary and disruptive to most.

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Educational gap -

The continued emphasis on the imperial system in schools means that generations of Americans have grown up without strong familiarity with the metric system, perpetuating its limited use. Indeed, the metric system is seldom taught in American institutions.

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Legislative inertia -

Despite various legislative efforts to promote metrication, none have had the strong enforcement that is necessary to compel a nationwide transition. This has led to legislative inertia for many decades.

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Continued use -

As time goes on, more and more everyday items, infrastructure, and official regulations rely heavily on the imperial system. It has been solidified in everyday life, and it makes the prospect of switching to the metric system seem less urgent and more disruptive.

Sources: (Britannica) (NASA Science) (SimScale) (US Metric Association)

See also: How to actually measure time

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