In-Between Densities

Definition

"In-between" densities is Jane Jacobs's name for the band of residential densities "fit neither for suburban life nor for city life. They are fit, generally, for nothing but trouble" (Jacobs 1961, p. 209). The band opens where semisuburban character fails — "above these semisuburban densities, the realities of city life can seldom be evaded" (p. 209, roughly 20 dwellings/net acre) — and closes where "genuine city life can start flourishing," which she judges "numerically… somewhere around the figure of 100 dwellings to an acre" under otherwise favorable conditions, while stressing that "a numerical answer means less than a functional answer" and that 100 "will be found to be too low" in general (pp. 210–211). The band is the engine of the gray belts: "The tremendous gray belts of relatively low density that ring our cities, decaying and being deserted, or decaying and being overcrowded, are significant signals of the typical failure of low densities in big cities" (p. 208).

The concept's supporting analysis is the density/overcrowding distinction ("high densities mean large numbers of dwellings per acre of land. Overcrowding means too many people in a dwelling for the number of rooms it contains… 'highdensityandovercrowding,'" pp. 205–206), the demonstration that the most successful districts carry the highest dwelling densities (North End 275; Brooklyn Heights 125–174; Rittenhouse Square 80–100, pp. 202–206n), and the two-sided ceiling: above roughly 200 dwellings per acre, "standardization of the buildings must set in. This is fatal" (p. 216) — unless high ground coverage reconciles density with variety, as Greenwich Village's 60–80% coverage does (p. 214). Low ground coverage, high density and building variety are "conditions that are incompatible with one another… The thing is a built-in contradiction" (p. 215).

Key Thinkers

• Jane Jacobs — the concept's author: density as "a matter of performance," measured against Lincoln's legs (1961, pp. 207–208).
• Henry Whitney (not yet paged — see log) — the architect whose combinatorial work proved "it is physically impossible to get above low city densities (40 to an acre or thereabouts) without standardizing all but a minute token of the dwellings — unless ground coverages are increased" (p. 215).
• Lewis Mumford (not yet paged — see log) — the Garden City theorist whose 100–125 persons per acre prescription Jacobs shows to be "in-between" density in dwelling terms (p. 210n).

Related Concepts

• mixed-primary-uses — the escape condition: a district escapes "in-between" when its dwellings "are dense enough to do a good primary-diversity job" (p. 211).
• towers-in-the-park — the institutional form the band produces when planned: low coverage plus high density forcing rigid standardization (Stuyvesant Town at 125 units/acre on 25% coverage, p. 214).
• hyperdensity — the contemporary remedy-discourse on the band's upper side.
• missing-middle-housing — the twenty-first-century programme for escaping the band from below, via ground coverage and type variety rather than towers.
• urban-sprawl — the band's outer edge, where "the semisuburbs… are a bad long-term bet, destined to become gray area" (p. 208).

Source Support

Sources in the wiki that discuss this concept:

• The Death and Life of Great American Cities (Jacobs 1961) — the concept's chapter (Ch. 11, pp. 200–220): the density/success inversions (pp. 202–204); the density-figures footnote (p. 206n); the overcrowding confusion traced to Garden City theory (pp. 205–206); the performance criterion and the Lincoln legs answer (pp. 207–208); the "in-between" definition (pp. 209–210); the Back-of-the-Yards exception (p. 210); the 100-dwelling functional floor (pp. 210–211); the standardization ceiling at ~200/acre (pp. 216–217); ground-coverage arithmetic (pp. 214–215); Whitney's impossibility result (p. 215); the North End's 275 with variety (p. 217); the emotional bases of density doctrine (pp. 220–221).

Source Support linking rule: All entries in this section must be wikilinks to source note pages in wiki/source-notes/ using the source-notes/ path prefix. Never link to raw files — raw files are not wiki pages.

This page requires fuller treatment — created at the Jacobs ingest; awaits the density-economics literature and the wiki's own hyperdensity and missing-middle-housing registers as the contemporary continuation.

Open Questions

• Jacobs's band is defined functionally (density sufficient to generate diversity, insufficient to be suburban). Wentling's walk-up datum — "a neighborhood with three-story walk-ups can achieve a density similar to an urban area with high rises" (p. 243) — supplies the type-variety half of her reconciliation. Do the wiki's two sources jointly yield a density policy rather than a density number?
• Is the "in-between" band a natural category or a historical artifact of the mid-century American city? The wiki's real-existing-suburbia and post-suburban-densification registers describe dense peripheries that thrive politically — are these escapes from the band, or the band's later rehabilitation?