Boise in context: Street-network sprawl trends

Boise in context

2.83.54.24.9<19751976–19901991–20052006–2020SNDi of street additions
2.83.54.24.9<19751976–19901991–20052006–2020SNDi of entire street network
BoiseIdaho (Region)United States (Country)

The chart above shows SNDi trends for new street additions (left panel) and the entire network (right panel), with Boise plotted against Idaho and United States. All three follow the same trend in new construction, suggesting a shared regional pattern of development. Most recently, Boise's incremental SNDi fell from 4.17 to 3.42 between 1991-2005 and 2006-2020. In terms of the aggregate network, Boise ranked 1st out of 2 cities in Idaho and 202nd out of 333 in United States as of 2020.

New Street Additions (2006–2020)

SNDi value
3.42
Rank in United States
77th of 333
Rank in Idaho
1st of 2

Entire Network (Aggregate)

SNDi value
3.51
Rank in United States
202nd of 333
Rank in Idaho
1st of 2

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

What about similarly populated cities?

3.244.85.6<19751976–19901991–20052006–2020SNDi of street additions
3.244.85.6<19751976–19901991–20052006–2020SNDi of entire street network
BoiseLucenaWakefield

In new street additions, Boise and Wakefield both built increasingly disconnected streets from 1975 through 1991-2005, then improved, while Lucena fluctuated in its street-construction patterns. Looking at the full network, Lucena and Wakefield both became progressively more disconnected, while Boise grew more disconnected from 1975 through 1991-2005, then improved. Boise and Lucena have been growing further apart in their street-network character since 1975.