Which side of the road you drive on is not a law of physics. It is a frozen political, military, and postal habit. Britain wrote keep-left into the Highway Act of 1835. Pennsylvania fined wagoners two dollars for failing to keep right on the Philadelphia–Lancaster Turnpike in 1792. Napoleon did not put traffic into the Civil Code. Henry Ford did not put America on the right. Japan copied a British railway. Sweden switched overnight on 3 September 1967 Dagen H after voters had said no. The 1949 Geneva Convention never picked a side for the Earth. It only said each country had to pick one.

0:00 Four-Fifty on Kungsgatan
0:27 Not a Law of Physics
1:05 A Rider's Habit
2:16 A Wagon's Fine
4:07 Napoleon Did Not Write This
5:27 A British Railway, Not a Colony
7:26 Dagen H
10:31 Why the World Did Not Pick One
12:01 Next time: the barcode was built for trains, not groceries

Made to Standard (@MadeToStandard) — documentary histories of hidden infrastructure, and the standards that made it inevitable.

Subscribe for the next episode: The Barcode Was Built for Trains, Not Groceries.

Sources
Highway Act 1835 (5 & 6 Will. 4 c. 50), s. 78 as enacted. https://www.legislation.gov.uk/ukpga/Will4/5-6/50/section/LXXVIII/enacted
London Bridge Act 1756 (29 Geo. 2 c. 40): east-side clause as commonly quoted; a bridge rule, not a national code.
Statutes at Large of Pennsylvania, Act of 9 April 1792, § XXI: keep to the right-hand side; $2 forfeiture. palrb.gov
Richard F. Weingroff, “On The Right Side of the Road,” FHWA (Albert C. Rose). https://highways.dot.gov/highway-history/general-highway-history/right-side-road
M. G. Lay, Ways of the World (Rutgers, 1992).
Peter Kincaid, The Rule of the Road (Greenwood, 1986).
Brian Lucas, “Which side of the road do they drive on?” http://brianlucas.ca/roadside/
Edward Planta, A New Picture of Paris (1827).
French keep-right: décret 10 August 1852; décret 19 January 1933.
Convention on Road Traffic, Geneva, 19 September 1949, Article 9(1). UNTS vol. 125, p. 3.
Japan, UN notifications on Okinawa (12 June 1972; 21 August 1978). Same UNTS status page.
New York Times, U-Turn for Okinawa,” 5 July 1978.
Japans first railway: Shimbashi–Yokohama, 14 October 1872; Edmund Morel; left-running.
道路取締令, Home Ministry Ordinance No. 45, Dec 1920 / Jan 1921.
Folkomröstningen 16 October 1955: SCB / Swedish Election Authority.
Riksdag, 10 May 1963: 294–50 as later tallied; Baldwin, Highway Research Record 234 (1968).
Sveriges Radio, “50 r med högertrafik.”
BBC Worklife, Maddy Savage, 18 April 2018 (Palme; 360,000 signs; 628 million kronor; 157 Monday accidents; 1,077 deaths in 1967).
H-dagurinn: Iceland, 06:00, 26 May 1968.
BBC News / The Guardian, Samoa, 7 September 2009, 06:00.

Archive stills: Kungsgatan 1967 (Jan Collsiöö / Wikimedia, PD-Sweden); Högertrafikmärke (Wikimedia, see file page); 1955 NEJ sign (Wikimedia, File:Vote_no.jpg); Conestoga wagon (Carol M. Highsmith / LoC); Pennsylvania 1792 § XXI (palrb.gov); 1908 Model T (Grogan / LoC); Yokohama railway triptych, c. 1872 (Hiroshige III / LoC). Diagrams: original for Made to Standard. Full still credits: stills-ep05/SOURCES.md.

AI tools were used for narration and video assembly. Historical photographs and prints are real archive images. Diagrams are original graphics, not photographs of events. No photoreal generated Dagen H crowds. A licensed Palme-at-the-microphone still and Okinawa 730 uncovering stills were not in hand; type cards were used.

Music: Event Horizon — The Grey Room — YouTube Audio Library (attribution not required). Reused from Episodes 1–4; a different Grey Room / Density & Time bed could not be fetched onto disk without a browser / YouTube Studio.