According to the US Central Intelligence Agency (CIA) factbook, “only three countries – Burma (former name for Myanmar), Liberia, and the US – have not adopted the International System of Units (SI, or metric system) as their official system of weights and measures”. 1 The key word in this sentence is “official”. It does not mean that they do not use the metric system. In fact, Myanmar and Liberia use metric speed limits unlike the UK.
Myanmar
The World Health Organization (WHO) road safety page for Myanmar provides the following advice on speed limits in Myanmar:
“Don’t drive over speed limits (urban road speed limit 48 km/hr (sic), rural road speed limit 80 km/hr (sic), and 100 km/hr (sic) for expressway). While raining, don’t speed over 60 km/hr (sic).” 2
Wikimedia Commons shows an image of a 48 km/h speed limit in Myanmar. 3
The International Drivers Association’s Myanmar Driving Guide 2022 tells you that “Myanmar uses the kilometers (sic) per hour system for measurement.” 4 and explains Myanmar’s speed limits in the following words:
“The general speed limit in the Myanmar expressway is 100 kilometers (sic) per hour, unless stated otherwise. In urban areas, the speed limit is 48 kilometers (sic) per hour, while in rural areas, the speed limit is 80 kilometers (sic) per hour due to less traffic.” 4
Liberia
The International Drivers Association’s Liberia Driving Guide tells you that “As for Liberia, the country belongs to the 179 countries (91% of all countries) that use kilometers (sic) per hour.”. 5 The Guide explains that the speed limit on rural roads is 25 km/h and the speed limit on urban/town roads is 45 km/h. 5
The Global Road Safety Facility provides a Road Safety Country Profile for Liberia. On this page, it tells you that the current speed limit is 40 km/hon urban roads, 56 km/h on rural roads and 72 km/h on motorways. 6
Conclusion
Many have misinterpreted the CIA statement and claimed that the US, Liberia and Myanmar are the only countries that do not use the metric system. This is untrue. They use the metric system, but they have not officially adopted the metric system. The US uses inter alia the metric system for science, manufacturing and nutrition information.
Despite the lack of official adoption of the metric system, Liberia and Myanmar have successfully implemented metric speed limits whereas the UK has not. Over 90% of all countries use km/h for speed limits. This includes all the big Commonwealth countries. Following the UK’s lead on metrication, they have successfully adopted metric speed limits unlike the UK. So why has the UK found it so hard to switch from mph to km/h?
Sources:
- https://www.cia.gov/the-world-factbook/references/weights-and-measures/
- https://www.who.int/myanmar/activities/messages-for-safety-on-myanmar-roads
- https://commons.wikimedia.org/wiki/File:Speed_limit_road_sign_in_Myanmar.jpg
- https://internationaldriversassociation.com/myanmar-driving-guide/
- https://internationaldriversassociation.com/liberia-driving-guide/
- https://www.roadsafetyfacility.org/country/liberia
Metric Views 
The CIA Handbook information goes back to the 1970s and has never been updated since and this old information is continuously and erroneously repeated year after year.
In 2013, Myanmar established SI as its official system and in 2018, Liberia became the last country on earth to establish SI as its official system. The US made SI official in 1975. Thus at this time ALL countries are officially metric.
However, not all countries even though officially metric are practically metric in use. The US, Belize and a number of other Caribbean Island nations have been slow in implementing metric units. Myanmar and Liberia have made some progress, but only because they are surrounded by metric countries. They produce very little in the way of goods and must import from neighbouring metric countries and have to accept the metric products without modification. For example automobiles with metric only instruments.
In rural areas of these countries petrol is sold out of jars and 20 L Jerry cans only in built up urban areas will one find petrol stations. In Myanmar, these stations have been selling in litres for a number of years. But, in Liberia they are still in US gallons.
I believe in both cases, the metric system is in full use for weather reporting.
The use of the kilogram in the market is lacking as traditional units are still in use in Myanmar and USC is still used in Liberia.
Due to extreme poverty in both of these countries metrication will be slow.
It is interesting to note the situation in Belize. Even though this country is on the list of fully metricated countries, it appears to be the least metricated country on earth. Despite SI being its official system, everything operates in USC, not imperial.
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You say that 90% of countries use metric speed limits. That implies that 20 or so don’t – I didn’t think it was that many?!
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Both Myanmar and Liberia have officially adopted the metric system (SI) as Daniel says.
‘https://metricviews.uk/2018/05/31/liberia-joins-the-club/’
‘https://worldpopulationreview.com/country-rankings/countries-that-dont-use-the-metric-system’
‘https://www.reddit.com/r/Metric/comments/11c84zm/good_news_from_liberia_and_myanmar/’ various other citations, surely not all fake news.
Now, maybe it is not clear if they actually ‘rubber stamped’ this in precise legal and official jargon or if the issue was blocked before whatever passes for accent into law, but surely someone in the world would know for sure????
What is for certain is that it will be an awful long time before these (because of poverty) also USA and UK because mostly of arrogance, become anywhere near what could be called “substantially complete” metrication.
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@BrianAC – The question of whether or not a country uses the metric system is extremely complex. Issues that need to be taken into account include a note the units of measure mandated for commercial purposes, the units of measure that the courts will accept without question should a dispute arise, the units of measure taught in the schools, the units of measure used in the press and so on. Many of these issues are subjective and so are not suitable criteria unless one person (or one team) assesses the metric using the same criteria across ALL countries.
When, in 1975 NIST published a list of countries that used the metric system, their criteria was that a law had been passed in the country concerned that the metric system was the legal default system on units in that country. The same criteria was used by Vara in his PhD thesis ibn 2011. (See https://commons.wikimedia.org/wiki/File:Metrication_by_year_map.svg).
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