Philadelphia in context: Street-network sprawl trends

Philadelphia in context

2345<19751976–19901991–20052006–2020SNDi of street additions
2345<19751976–19901991–20052006–2020SNDi of entire street network
PhiladelphiaPennsylvania (Region)United States (Country)

The chart above shows SNDi trends for new street additions (left panel) and the entire network (right panel), with Philadelphia plotted against Pennsylvania and United States. The SNDi of new construction in Philadelphia followed a zig-zag trend with an overall increase, compared to Pennsylvania which rose steadily and United States which peaked in 1991-2005. Most recently, Philadelphia's incremental SNDi rose from 2.82 to 3.34 between 1991-2005 and 2006-2020. In terms of the aggregate network, Philadelphia ranked 2nd out of 16 cities in Pennsylvania and 11th out of 333 in United States as of 2020.

New Street Additions (2006–2020)

SNDi value
3.34
Rank in United States
69th of 333
Rank in Pennsylvania
5th of 16

Entire Network (Aggregate)

SNDi value
1.71
Rank in United States
11th of 333
Rank in Pennsylvania
2nd of 16

Rankings go from most connected to most disconnected — rank 1 is the most connected.

What about similarly populated cities?

23456<19751976–19901991–20052006–2020SNDi of street additions
23456<19751976–19901991–20052006–2020SNDi of entire street network
PhiladelphiaTaichungQuito

In new street additions, Philadelphia and Taichung both fluctuated in its street-construction patterns, while Quito built increasingly disconnected streets from 1975 through 1976-1990, then improved. For the full street network, though, all three cities follow the same trend. Philadelphia and Taichung have been growing further apart in their street-network character since 1975.