Cambridge is changing. While politicians decry the loss of the middle class, the real change in Cambridge is that it is becoming a city of roommates rather than families, one where, whether you own or rent, the cost of housing keeps increasing.
In 1950, according to census data, 87% of Cambridge households (those not living in group quarters such as dormitories) were families, those related by birth, marriage or adoption. By 2010, families made up less than 40% of Cambridge households.
While Cambridge's population has been rising along with the number of households, the number of families has remained largely unchanged since 1980.
In the same 60 years, the number of residents between the ages of 20 and 39 has grown by almost 60%, while other age groups have declined.
Over 50% of Cambridge's population is between the ages of 20 through 39. For the United States as a whole, that age range encompasses 27% of the population.
Cambridge has become a city composed more of working people at technical, professional or managerial jobs.
Over the last decade, the income required to purchase a home in Cambridge has increased. For single family homes, it requires 30% more income than it did 10 years ago.
The income required to rent a Cambridge apartment has also increased. A single bedroom apartment is 30% more expensive than it was a decade ago. According to Cambridge's calculations, which assume that 30% of ones income can be devoted rent, an income of $71,800 is required to rent a one bedroom apartment.
Cambridge, as would be expected in an economic environment where housing is increasingly valuable, continues to add to its housing stock.
Yet Cambridge's population density, after declining from 1950 to 1980, has only now returned to that of 1960.
A note about data and sources: Most of these data are derived from Cambridge Community Development's excellent Statistical Profile of Cambridge. Those wishing to use the data presented here would find reading the caveats and explanations in that report useful. Census methods are complex, and deriving big picture numbers are not straightforward.