Fluid distribution systems, and particularly those for distributing liquids into apparatuses containing parallel flow trays for carrying out vapor-liquid contacting, are described. Representative fluid distribution systems comprise one or more extended troughs having a plurality of outlet spouts that are aligned for distribution to a vapor-liquid contacting deck zones of a parallel flow stage. The trough(s) may be orthogonal to liquid distribution pans which are in alignment with outlet spouts (e.g., in discrete outlet spout zones) of the trough(s).