This article contributes to the debates surrounding ‘New African Economic
History’ by exploring the feasibility of constructing a time series of economic
growth in Nigeria spanning the 20th century. Currently most datasets for African
economies only go back to 1960. The sources for their creation exist, but these
valuable colonial data remain underutilized. This is a first exploratory paper in a
project aiming to create measures of economic growth through the 20th century
for a sample of African economies. The paper offers a systematic discussion of
the different available datasets on population, agricultural production and income
for the country. It finds that the existing data, often presented as facts, are more
accurately described as projections based on assumptions. If these assumptions
are already made in the production of the data, this precludes empirical testing of
important questions. The main lesson is that any African economic history
investigation must both begin and end with a critical analysis of the quantitative
data, and must further be supported by careful qualitative evaluation.