This month, we are pleased to devote The Urbanist to Unbuilt San Francisco, an ambitious five-venue exhibition that provides an opportunity to confront visions for the region that never came to pass. Attempts to reconfigure San Francisco according to evolving notions of progress, beauty and justice have often proved controversial — and even traumatic.

The northeast neighborhoods of San Francisco — North Beach, Telegraph Hill, Russian Hill, Fisherman’s Wharf and the edges of Chinatown — have some of the city’s highest densities of residents, workers and tourist activities. Yet there are currently no major plans to increase transit capacity serving the area. SPUR convened a community workshop to assess transit needs in these neighborhoods.

Innovative design solutions can better accommodate the changing — and sometimes surprising — demographics in cities, including a rising number of single people. In New York, a third of all households are single people living alone. In San Francisco, it’s 38 percent. Why aren’t we designing housing for that demographic?

Today, Silicon Valley receives the country’s largest share of venture capital investment — but New York may be catching up. It’s not official economic development strategies that should worry the Bay Area. More important are the underlying fundamentals supporting New York City’s growth: its ability to attract talent, its urbanity and its existing industry mix.