1928, Fiftieth Number
United States. Bureau of Foreign and Domestic Commerce and United States. Bureau of the Census. "1928, Fiftieth Number," Statistical Abstract of the United States (1928). https://fraser.stlouisfed.org/content/?item_id=22036&filepath=/files/docs/publications/stat_abstract/sa_1928.pdf, accessed on May 20, 2018.
From title page: "Commencing with this issue, the Statistical Abstract will be designated by the year in which it is published. Consequently there was no issue bearing date 1927."