This paper uses annual data spanning 1870 to 1930 on a set of variables correlated with business conditions to construct an index of real economic activity in Switzerland. We extract an estimate of the common component of the data series using principal components analysis and the unobservable variables approach proposed by Stock and Watson (1989, 1991). The resulting index is similar to that constructed by Andrist et al. (2000) but displays more variation over time and is available for a longer time period. Moreover, it is less volatile and covers a longer time period in the 20th century than the estimate by Ritzmann-Blickenstorfer (1996).