This paper presents the results of a measurement study of the T1 NSFNET backbone. We first discuss the measurement environment and approach to data collection. We then present measurements results for: long-term growth in traffic volume, including attribution to domains and protocols; trend in average packet size on the network, both over long and medium term intervals; most popular sources, destinations, and site pairs; traffic locality; international distribution of traffic; mean utilization statistics, both of the overall backbone as well as of specific links of interest; and delay statistics.