The price of gas relative to the price of milk has been trending upwards for the past 40 years:

The first diagram shows price trends with both gasoline and milk prices normalized so that 2002=100. It shows that the price of gas relative to the price of milk has increased 30 percent in the past 10 years, and doubled since the early 1970s.

The rise in gas prices looks dramatic in part because I have played fast-and-dirty with my vertical axis, starting at 0.6 to magnify the impact of price changes. I also chose my starting point with care. A longer time trend shows a different story.

Yes, the relative price of gas and milk has risen since the early 1970s, but that was an exceptional time. Gas prices were lower then than they have ever been, before or since.

The point is that grounding our image of "the past" in the 1970s can be highly misleading.

One of my students this term, Kristian Laanamets, produced a graph with 2006 General Social Survey data that makes a similar point (used with permission). Kristian's graph shows the proportion of people, by age, raised by both of their biological or adoptive parents:

The people most likely to be raised by both parents are 55 to 64 year olds, people born between 1942 and 1951.

The 1950s, like the 1970s, was unusual in many ways. There have always been children born to single mothers. Prior to the 1950s, a significant proportion of the population also lost a parent due to disease, war, or other circumstances. Only with the introduction of antibiotics and other health care advances in the first half of the last century did the two-parent family begin to approach a universal norm.

Historical data is like science fiction. It is a way of exploring a world like ours, only different. It gives a sense of possibilities, what the world might be like under different circumstances.

Until recently, exploring the past meant spending hours in libraries pouring over dusty archives. Now a group of enterprising historians and economists, with the help of funding from various agencies, are changing all that.

Peter Baskerville, a historian at University of Victoria, sent me a list of Canada's historical census projects. These projects are taking random samples of past censuses, entering the data in a standard format, and making it available on-line. Here is Peter's list:

For 1911 and for information on 1921-1951: ttp://ccri.library.ualberta.ca/enindex.html



For 1901: http://web.uvic.ca/hrd/cfp/data/index.html



For 1871 and 1891 please see: http://www.uoguelph.ca/~kinwood/



For 1851 and a full count 1881 please see: http://www.prdh.umontreal.ca/census/fr/uguide/1881history.aspx



For international data see: https://international.ipums.org/international/ and http://www.nappdata.org/napp/

Economists involved in this initiative include Kris Inwood at University of Guelph, and the late Mary MacKinnon of McGill University. I will write more on their work later; today is a working-on-teaching-stuff day. [Update: this list omits Gordon Darroch, who did some of the pioneering work on the 1871 census data].