In the early 1980s, so many people began to live on our streets that average citizens from coast to coast could not help but notice a phenomenon not seen in the US since the height of the Great Depression. The roots of this emerging disaster were firmly planted in the 1970s, when the expansion of affordable housing that started primarily for World War II veterans came to a crashing halt. At the same time, several smaller but significant causes of homelessness came together in a kind of perfect storm.

In The Tipping Point: How Little Things Can Make a Big Difference, Malcolm Gladwell tells the story of how social epidemics spread and eventually reach a “tipping point,” using disease epidemics as his framework. He identifies three principles that drive social change, “one, contagiousness; two, the fact that little causes can have big effects; and three, that change happens not gradually but at one dramatic moment…” Gladwell argues that the tipping point occurs at that moment when, like a roller coaster slipping over the top of its climb, the process of change dramatically accelerates. Gladwell also cites three factors that drive the roller coaster up the hill—the right people, a “sticky” concept, and the right context.

This framework is useful in assessing both the rise of homelessness in the US and the impact of subsequent efforts to do something meaningful about it. Think of it as the roller coaster with double hills. As we tipped over the first hill in the early 1980s, multiple causes intersected and led to the emergence of significant homelessness. Almost 25 years later, we are chugging up the second hill, working to reduce the number of people who are homeless, and even dreaming that we might hit tipping point number two and head down the hill toward ending widespread homelessness in the U.S.