The ThemeRiver™ visualization helps users identify time-related patterns, trends, and relationships across a large collection of documents. The themes in the collection are represented by a “river” that flows left to right through time. The river widens or narrows to depict changes in the collective strength of selected themes in the underlying documents. Individual themes are represented as colored “currents” flowing within the river. The theme currents narrow or widen to indicate changes in individual theme strength at any point in time.