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From: "Randy Klear (DMD)" <rklear@Census.GOV>
Newsgroups: alt.folklore.urban
Subject: Re: Missing US Census?
Date: Wed, 2 Oct 1996 20:36:57 -0400

Usually I only lurk in a.f.u., and then on my own time with a commercial account, but for this one, I had to try to look official...

On 2 Oct 1996, Ian Munro wrote:

>      There is a "missing" US Census.  During the 1970s the census people 

>      discovered that one census from the 1950s was stored in an electronic 

>      medium that over time had become completely obsolete.  Because of 

>      sloppy data management no one will ever be able to read this census;

>      the information exists but is now inaccessible.

The original registers from the 1950 census (only one in the 1950s) are all on microfilm in the hands of the National Archives and Records Administration. Some tabulation files kept on computer tapes of that period were lost because suitable tape drives no longer exist, but the tabulated results themselves were printed and distributed to the public. They are available at many larger libraries.

All primary census records since 1790 are on NARA microfilm, with two major exceptions:

1. the 1890 census, most of which was lost in a 1921 fire at the old Commerce Department building in Washington; and
2. certain records from the 1790-1810 period lost when British troops burned the city in 1814.

The processing procedures used from 1960-1990 required microfilming up front, after which the computer data was obtained by optical scanning of the microfilm, and the microfilm went to NARA.

> I quizzed her a bit about
> the "completely obsolete" technology bit; she seemed to remember it as
> being a software problem instead of a hardware problem, but she wasn't
> sure.

It's a combination of the two. Storage media have changed quite a bit physically from the metal open-reel tapes used in the 1950s and 1960s, and no one builds drives that can read them anymore. Even if someone built such a drive, you'd have to write custom software to interpret the file formats used back then, *if* you can find documentation for them.

The problem of long-term computer storage and media obsolescence is an interesting one. The January 1995 _Scientific American_ (think that's the right month) has an excellent general-audience article on the topic by Jeff Rothenberg.

I know the Census Bureau made one or two attempts to copy its data storage libraries from old to new media. The last agency-wide project I know of was in the late 1970s, when the last metal-tape stuff was copied to 6250 bpi phase-encoded mylar tape (IBM 3420 type; tape drives for this are still commercially available). Some tapes (a low proportion, as I remember) were unsalvageable even then.

To sum up: 1) some computer tapes with old census tabulations are no longer around; 2) those census tables were published on paper anyway; 3) the raw data is still on microfilm, and in theory we could recreate the whole thing if we had to.

Randy Klear                              rklear@census.gov
US Bureau of the Census                  rklear@infi.net
Decennial Management Division            tabularasa@aol.com