This data set represents the average monthly runoff (mm) from McCabe and Wolock's Runoff Model over the period of record, 1951-2000 compiled for two spatial components of the NHDPlus version 2.1 data suite (NHDPlusv2) for the conterminous United States; 1) individual reach catchments and 2) reach catchments accumulated upstream through the river network (i.e., watersheds). This dataset can be linked to the NHDPlus version 2 data suite by the unique identifier COMID. The source data were produced by McCabe and Wolock (in review). Units for the average monthly runoff (mm) from McCabe and Wolock's Runoff Model 1951-2000 are millimeters per year. Reach catchment information characterizes data at the local scale. Reach catchments accumulated upstream through the river networks characterizes cumulative upstream conditions. Network-accumulated values are computed using two methods, 1) divergence-routed and 2) total cumulative drainage area. Both approaches use a modified routing database to navigate the NHDPlus reach network to aggregate (accumulate) the metrics derived from the reach catchment scale. (Schwarz and Wieczorek, 2018).