[Update: I'm interested in why so many people are searching for the population of Boston in 2004. Shoot me an email and let me know. Thanks--The Editor. Entry edited 28 February 2005]
[Update: The Boston Redevelopment Authority has the 2000 Census data broken down by neighborhood. You can find it here. 18 March 2005]
I've had quite a few people searching for the population of Boston in 2004. The 2000 Census showed a population of 589,141, an increase from 1990's 574,823. The Boston metropolitan area population is around 2.9 million. Anything more recent is an estimate. My guess is that Boston's population has increased slightly since then based mostly on my own perceptions, nothing more. In past years, a state census (or was it a city census?--I can't remember which) would be conducted mid-decade. I believe this practice ended in the 1960s. Boston's population peaked in 1950, at 801,444.
The mid-decade census did reveal some interesting trends that might have otherwise gone unnoticed. For example, Boston's population declined between 1930 and 1940, from 781,188 to 770,816. The 1935 census showed that the population increased above the 1930 number. My guess is that in the first years of the Depression, people moved back into Boston with relatives or in search of lower rents. Of course, the difference in population could be an artifact of differences in the counting process between the federal and local censuses. But Boston directories of the time list people by street and then by address. In the neighborhood I looked at, Boston's West End, new people with the same last names as people listed in the 1930 directory begin to appear in in later directories--1933, 1934, 1935, etc.--as living at the same address which would seem to confirm the relatives moving in hypothesis.
We tend to think of population in the point-to-point ten year intervals dictated by the U.S. Census, but in reality population has its ebbs and flows within those decades. The implications are probably slight in the larger scheme of history, but it would be interesting to have better correlations between specific events and population shifts. In Boston, knowing the population in 1965 and 1975 might be more valuable than knowing the population in 1960 and 1970 or 1970 and 1980 for example, given that the 1965 to 1975 time frame brackets more closely two of the more turbulent events in Boston's history, the redlining practices which really began to effect Boston neighborhoods in the mid 1960s and the beginning of school busing in the early 1970s. There are other ways to judge population movement of course--property sale records, school enrollments, voting lists, etc. but the census provides the most readily available apples to apples comparison.