Tacoma in context: Street-network sprawl trends

Tacoma in context

3456<19751976–19901991–20052006–2020SNDi of street additions
3456<19751976–19901991–20052006–2020SNDi of entire street network
TacomaWashington (Region)United States (Country)

The chart above shows SNDi trends for new street additions (left panel) and the entire network (right panel), with Tacoma plotted against Washington and United States. The SNDi of new construction in Tacoma peaked in 1976-1990, compared to Washington which peaked in 1976-1990 and United States which peaked in 1991-2005. Most recently, Tacoma's incremental SNDi fell from 6.23 to 5.62 between 1991-2005 and 2006-2020. In terms of the aggregate network, Tacoma ranked 4th out of 8 cities in Washington and 143rd out of 333 in United States as of 2020.

New Street Additions (2006–2020)

SNDi value
5.62
Rank in United States
285th of 333
Rank in Washington
7th of 8

Entire Network (Aggregate)

SNDi value
3.03
Rank in United States
143rd of 333
Rank in Washington
4th of 8

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

What about similarly populated cities?

246<19751976–19901991–20052006–2020SNDi of street additions
246<19751976–19901991–20052006–2020SNDi of entire street network
TacomaHafar Al-BatinKas

While Hafar Al-Batin and Kas both built increasingly disconnected streets over time, Tacoma built increasingly disconnected streets from 1975 through 1976-1990, then improved in new street additions. For the full street network, though, all three cities follow the same trend. Tacoma and Hafar Al-Batin have been growing further apart in their street-network character since 1975.