An extraordinary investigation into shade, bringing together science, history, urban design, and social justice to change the way we think about this critical natural resource that should be available to all.

On a 90-degree day in Los Angeles, bus riders across the city line up behind street signs and telephone poles, looking for the relief of a little shade. Such scenes play out in cities across the United States every summer, and, as Sam Bloch reveals, whether or not shade is easy to find has a lot to say about a neighborhood's income level, the health of its community, and the resources its residents have at their disposal. In some cases, finding shade can be a matter of life and death.

Shade has long been a staple of human civilization, and the world's oldest cities have it baked into their DNA. In Mesopotamia and Northern Africa, cities were built densely so that courtyards and public passageways were in shadow in the heat of the day. Greeks and Romans famously philosophized in shady agoras, and property owners in Renaissance Bologna were required to provide shade by building over the sidewalk. Even today, in sunny Seville, Spain, political careers are ruined when leaders fail to put out the public shades that hang above sidewalks in time for summer heat.

But, in the U.S., the arrival of air conditioning took away the impetus to design for shade as our cities grew. Though a few heroic planners, engineers, and architects developed shady designs for efficiency and comfort, the removal of shade trees in favor of wider roads and underinvestment in public spaces created a society where citizens retreat to their own cooled spaces, if they can, or face dangerous heat outdoors. Bloch notes what we stand to lose by devaluing shade: Heatwaves are now the country's deadliest natural disasters with victims concentrated in poorer, less shady neighborhoods. Public health, mental health, and crime statistics are worse in neighborhoods without it. Simply put, shade makes communities.

Shade is an extraordinary tour de force that sheds light on a crucial subject that's just been waiting for us to see it.