Automatic zoning, in land use, is when the allowable use of land is set or altered based on some objective condition such as a street opening, land values, or local housing unaffordability level. Also called conditional zoning.
Background in US zoning law
Rezonings sometimes occur automatically...property may be downzoned or upzoned upon the happening of a future event. Reversionary zoning is sometimes used where the community wishes to assure itself that a developer engages only in the use granted by a rezoning. To do so, it may provide that if no one develops the property for a specific use within a set time or the if the newly allowed use ceases, the property's zoning classification will revert to its prior classification." "An ordinance might provide that happening of certain events will classify the property for a different use. For example...that a property zoned agricultural will be zoned residential upon the opening of a major street. This 'potential classification zone' has the advantage of giving property owners and others some indication of the plans of the city."
- [Juergensmeyer et al 2013]
Incentive zoning is similar in some respects to conditional zoning. In this approach, public benefits or amenities are obtained from a private developer in exchange for offering some incentive such as allowing greater height or number of housing units in a project.
Typical amenities include public spaces ("Privately owned public spaces" - POPs), parking, transit access
California State Bonus Density Law is an example. San Francisco's Home-SF program is its implementation of that law.
Performance zoning 
Another type of automatic zoning is performance zoning, where allowable land-use is determined by compliance with some specified outcome, often environmental or nuisance related. For example, a zoning ordinance might limit slopes beyond some percentage gradient from being developed or cleared.
Automatic upzones based on land value - Desire for Density
Desire for Density is a site and proposal created in 2019 by two Austin urban advocates:
- Dan Keshet is editor and chief author of Austin on Your Feet. He was a co-founder of Austin urbanist organization AURA.
- Chris Bradford is a land use attorney in the city of Austin and long-time blogger at Austin Contrarian.
It is based on ideas Keshet and Bradford originally presented at YIMBYtown_2017).
Shane Phillips @shanedphillips 10:21 AM - 8 Jan 2018
Replying to @DanKeshet @YIMBYwiki and 3 others
"Automatic upzones tied to land value! A boy can dream."Dan Keshet 🚶 @DanKeshet 10:22 AM - 8 Jan 2018
Replying to @shanedphillips @YIMBYwiki and 3 others
"This was @ChrisBBradford and my proposal at YIMBYtown '17. We're still writing it up."
from Desire for Density site:
"We can use Land Value Ratios directly to make zoning decisions based on objective data that will minimize price increases. The idea is simple: set an acceptable land value-to-unit ratio, and upzone whenever the ratio exceeds a chosen threshold (say, $150k per unit). By upzoning any area where land values per built unit are higher than the threshold, the land value ratio allows you to target the places where additional density is both most wanted by home shoppers and where it will have the biggest impact on affordability. Redoing this analysis every few years — or using an automatic trigger like the land value trigger — would let a city stay on top of problems as they arise, rather than needing to foresee changes in trend that will happen five, ten, or twenty years into the future."
Adaptable zoning and building code - Dan Doctoroff / Sidewalk Labs
from [Corwin 2017]:
"Cities can become more flexible and adapt to the needs of their residents. "Let me give you an example of adaptability in zoning laws. Why do we have zoning laws? Because there are uses of buildings that are incompatible with other uses of buildings. We don’t typically put factories next to schools, and, for the most part, we don’t put residences next to commercial buildings. There is little transparency about what is going on inside these buildings, so we classify them crudely. We do the same thing with building codes: We over-engineer buildings because we can’t actually monitor them over time. "Now imagine the digital networked age where technologies such as sensors and social networks help us better understand what’s going on. Cities can say, “You can do whatever you want in that building as long as your decibel level doesn’t go above X, and we’ll be monitoring it.” The ability to change uses and space quickly becomes possible, enabling the emergence of a whole set of new industries around flexible buildings that can be monitored, lowering cost and creating economic growth."
Austin Democratic Socialists of America proposal
from January 2018 "Austin DSA Housing Committee CodeNEXT Demands":
3. Deploy an Automatic Affordability Trigger
Directly link zoning to affordability through an automatic affordability trigger: When any neighborhood exceeds certain thresholds of unaffordability, automatically upzone it subject to the affordable housing bonus program and city investment in public or social housing, such as land trusts, housing cooperatives, and nonprofit housing.
- Corwin, Scott. "The urban optimist: Daniel Doctoroff on the future of cities." Deloitte Insights. January 23, 2017.
- Democratic Socialists of America, Austin chapter (DSA Austin 2018). "Austin DSA Housing Committee CodeNEXT Demands." January 2018. https://docs.google.com/document/u/1/d/1KD6JtmdeWubVfGOp-hCajUEbrMj5FqVqUhCwqBkdSJU/mobilebasic.
- Juergensmeyer, Julian and Thomas Roberts (2013). Land Use Planning and Development Regulation Law, 3rd edition. (Hornbook Series). Thomson Reuters, 2013.
- McCormick, Tim. "A brief exchange with Tim O'Reilly about /algorithmic regulation.'" Blog post, 15 Feb 2015. http://tjm.org/2014/02/15/a-brief-exchange-with-tim-oreilly-about-algorithmic-regulation/.
- O'Riley, Tom. "Open Data and Algorithmic Regulation." chapter in Beyond Transparency," Code for America, 2013. http://beyondtransparency.org/chapters/part-5/open-data-and-algorithmic-regulation/.
- Weaver, Kent. "Setting and Firing Policy Triggers." Journal of Public Policy, Volume 9, Issue 3 July 1989 , pp. 307-336.
Governments increasingly use quantitative policy signals as automatic triggers for policy adjustments rather than simply to inform policy debate. This increased use of policy triggers cannot be explained simply by a technocratic desire to reduce workloads and regularize policy adjustments. Political objectives – notably desires to reduce conflict, bind future policymakers, and avoid blame – play an important role both in decisions to use policy triggers and in the selection of specific triggers. Using policy signals as triggers often leads to the politicization of statistics and to harmful rigidification of policy."
- Wikipedia. "Algorithmic regulation." https://en.wikipedia.org/wiki/Algorithmic_regulation.