Methods, apparatus, systems and articles of manufacture to extend a time range supported by a watermark are disclosed. Example watermark encoding apparatus disclosed herein determine which one of a plurality of timestamp cycles is to be represented by a timestamp of a watermark, the timestamp including a set of timestamp symbols, a first subset of data symbols and a second subset of data symbols. Disclosed example apparatus also modify the first subset of data symbols of the watermark based on a further timestamp symbol not included in the set of timestamp symbols of the timestamp, but not modify the second subset of data symbols based on the further timestamp symbol, the further timestamp symbol to identify the one of the plurality of timestamp cycles to be represented by the timestamp of the watermark. Disclosed example apparatus further embed the watermark in a piece of media.