Objective. Novel therapeutics and supportive care improved outcomes for metastatic non-small-cell lung cancer (mNSCLC) patients. Major advances over the past five decades include the introduction of combination chemotherapy, small molecules targeting mutant proteins, especially EGFR, and more recently immunotherapy. We aim to document real-world long-term survival over the past five decades. Methods. Survival statistics were extracted from the Survival, Epidemiology, and End Results (SEER) database for mNSCLC patients during 1973-2015. Two- and five-year survival (2yS and 5yS) were analyzed using Kaplan-Meier and proportional hazard models. Results. The study population consisted of 280,655mNSCLC patients diagnosed during 1973-2015. Longer survival was seen in younger, female, married, Asian/Pacific Islander race, adenocarcinoma, lower grade, more recent diagnosis, higher income, and chemotherapy-treated patients. 2yS increased during the study period from 2.6% to 12.9%, and 5yS increased from 0.7% to 3.2%. 2yS of patients <50 years of age rose from 2.1% to 22.8%, and their 5yS rose from 0.7% to 6.2%. 2yS of adenocarcinoma patients improved from 2.7% to 16.2%, and their improved 5yS from 1.1% to 3.9%. Conclusions. Between 1973 and 2015, there was a dramatic improvement in long-term survival, with an approximately five-fold increase in both 2yS and 5yS. Nonetheless, absolute numbers of long-term survivors remained low, with less than 4% living 5 years. This provides a baseline to compare long-term outcomes seen in the current generation of clinical trials.