Source: U.S. Bureau of Labor Statistics
Many series include both seasonally adjusted (SA) and not seasonally adjusted (NSA) data. In some cases, the NSA data will be updated but the SA data will not be updated. The reason is usually that the data series has not accumulated enough new seasonal factors to trigger an adjustment.The NSA series can be located here The FRED team is currently working on a new procedure to replace SA data that has not yet be updated with NSA data that has been updated.
Some seasonally adjusted series may exhibit negative values because they are created from a seasonal adjustment process regardless of the actual meaning or interpretation of the given indicator.
Federal Reserve Bank of St. Louis and U.S. Bureau of Labor Statistics, All Employees: Construction: Heavy and Civil Engineering Construction in Lake Charles, LA (MSA) [SMU22293402023700001SA], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/SMU22293402023700001SA, October 14, 2019.