Hoy No Circula: Mexico City's Plate-Based Driving Restriction
Mexico City started keeping cars off the road one weekday a week by the last digit of their plate in November 1989, after an ozone emergency, and made the rule permanent the following year. A compulsory emissions test every six months assigns each car a hologram, and that reading decides how hard the ban bites: holograms 00 and 0 drive every day, hologram 1 also rests two Saturdays a month, hologram 2 every Saturday. Saturdays were added on 5 July 2008, and when the metropolitan monitoring network pushes ozone past the contingency threshold the regional environment commission declares a 'Fase I' that pulls even exempt cars off the road. Thirty-seven years on, peer-reviewed evaluations have still not found that the air got cleaner.
No measured air-quality gain in the peer-reviewed record. Davis (Journal of Political Economy 116(1), 2008) found 'across pollutants and specifications there is no evidence that the restrictions have improved air quality', together with evidence that the ban raised the total number of vehicles in circulation and shifted the fleet toward high-emission cars. Davis (Scientific Reports 7:41652, 2017) found the July 2008 Saturday extension had virtually no discernible effect across eight pollutants, and no sign that drivers switched to metro, bus or light rail. Gallego, Montero and Salas (Journal of Public Economics 107, 2013) measured the workaround directly: an initial drop in car use followed by a rise in the household vehicle stock within eleven months.
🎓 Lesson
Ration driving by plate digit and households buy a second, usually older, car to fill the gap. The oldest scheme of its genre is also the one with the most evidence that it did not do what it was built to do.
Evidence🔬 Peer-reviewed
Scale🗺️ Regional
Sources
↗ Davis, 'The Effect of Driving Restrictions on Air Quality in Mexico City', Journal of Political Economy 116(1), 2008, pp. 38-81The load-bearing null result, abstract verbatim: 'In 1989, the government of Mexico City introduced a program, Hoy No Circula, that bans most drivers from using their vehicles one weekday per week on the basis of the last digit of the vehicle's license plate... Across pollutants and specifications there is no evidence that the restrictions have improved air quality. Evidence from additional sources indicates that the restrictions led to an increase in the total number of vehicles in circulation as well as a change in composition toward high-emissions vehicles.' Publisher page journals.uchicago.edu/doi/10.1086/529398; the author's own copy is at faculty.haas.berkeley.edu/ldavis/Davis%20JPE%202008.pdf but did not render from this desk, so the abstract was verified against this indexed mirror.
↗ Davis, 'Saturday Driving Restrictions Fail to Improve Air Quality in Mexico City', Scientific Reports 7:41652, 2017Dates the Saturday extension and grades it: 'Mexico City's driving restrictions were expanded to include Saturdays on July 5th, 2008.' and 'Overall, there is little evidence that the program expansion improved air quality.' Also the sentence this entry uses on enforcement: 'City police vigorously enforce the restrictions and vehicles violating the ban are easy to spot. Drivers caught violating the rules must pay a hefty fine and their vehicles are impounded for 48 hours.'
↗ SEDEMA, Ciudad de Mexico — Programa Hoy No CirculaThe operator's own programme page and the correct citation for the current rules. Direct fetch returned 503 from this desk on 2026-07-26; the rules were corroborated against the CAMe description and the 2026 press cited below, which agree on hours, coverage and hologram tiers.
↗ Comision Ambiental de la Megalopolis — 'El Programa Hoy No Circula que aplica en la Zona Metropolitana del Valle de Mexico'The metropolitan authority's own description, carrying the coverage and hours used in the snippet: 'Aplica en las 16 alcaldias de la Ciudad de Mexico y en 18 municipios conurbados del Estado de Mexico, de lunes a sabado de 5:00 a 22:00 h' ('It applies in the 16 boroughs of Mexico City and in 18 adjoining municipalities of the State of Mexico, Monday to Saturday from 5:00 to 22:00'), and the hologram rule: 'Los vehiculos con holograma 1 no circulan dos sabados del mes segun su terminacion, mientras que los vehiculos con holograma 2 no circulan ningun sabado del mes' ('Hologram 1 vehicles do not drive on two Saturdays a month according to their plate ending, while hologram 2 vehicles do not drive on any Saturday'). Direct fetch blocked (403); the carrying sentences were confirmed by search.
↗ Gobierno de Mexico / CAMe — Fase I de contingencia ambiental atmosferica por ozono en la ZMVMEstablishes who declares a contingency and that a declaration extends the driving ban. CAMe activated five ozone Fase I contingencies in 2025 alone (26 February, 18 March, 1, 23 and 25 April). The activation threshold is reported by Mexican press as 150 IMECA points for ozone, with a pre-contingency at 135, at which point 'Doble Hoy No Circula' reaches holograms 0 and 00; that numeric threshold is press-reported and is deliberately kept out of the snippet. Direct fetch blocked (403).
↗ El Financiero — 'Hoy No Circula: origen, historia y por que se instauro este programa en la CDMX'Origin detail: the programme began on 20 November 1989 as an emergency measure named 'Un Dia sin Auto' ('A Day Without a Car') during an ozone emergency, and was made mandatory and permanent by an accord published on 1 March 1990, alongside the introduction of biannual vehicle emissions verification. The exact 1990 date rests on Mexican press rather than on the Gaceta text, so the entry says only 'the following year'.
↗ adn40 — photo-enforcement cameras that sanction Hoy No Circula in CDMX (4 September 2025)The camera question, media-grade only: 'Estos dispositivos no solo sancionan a quienes exceden la velocidad, tambien detectan conductores que circulan sin respetar las restricciones ambientales' ('These devices do not only sanction those exceeding the speed limit, they also detect drivers circulating without respecting the environmental restrictions'), on a network described as more than 140 fixed cameras and radars plus mobile units, after CDMX restored economic photo-fines alongside the 2019 points-based fotocivicas. No official source confirming camera detection of Hoy No Circula was reachable, so this is not claimed in the snippet.
1001 Smart Cities (2026). “Hoy No Circula: Mexico City's Plate-Based Driving Restriction” — Mexico City, Mexico. The Smart City Atlas. https://1001smartcities.org/projects/mexico-city-hoy-no-circula/ (last verified 2026-07-26). Data: CC BY 4.0.
The underlying data is free to reuse with attribution — see the open data page.
