n. — Administration
a clinic, usually set up in a temporary location for a day, where people can donate blood.
Type: 5. Frequency — It appears that the earliest blood donor clinics in Canada were set up by the Red Cross during WWII. While blood donor goes back to at least the 1870s, this compound noun appears to be much younger.
The clinics and the term continue to enjoy a high prevalence in Canada (see, e.g. Chart 1), which makes the term a Canadianism in the North American context. Instances of blood donor clinic also appear in the US during the mid-1940s, but the term has fallen into relative disuse there, where the more common terms are blood bank and blood donation center.
See also COD-2, s.v. "blood donor clinic", which is marked "Cdn".
Images:

Chart 1: Internet Domain Search, 11 Sep. 2013