Beginning in 1834, an index of business activity by the Cleveland Trust Company provides data for comparison between recessions. Beginning in 1854, the National Bureau of Economic Research dates recession peaks and troughs to the month. But for the earliest recessions, there are no standardized indexes, and the data are considered unreliable. As the data get older, their reliability worsens.[8]http://en.wikipedia.org/wiki/List_of_recessions_in_the_United_States