BackgroundThe circumstances under which pneumonectomy should be performed are controversial. This study aims to investigate national trends in pneumonectomy use to determine which patients, in what geographic areas, and under what clinical circumstances pneumonectomy is performed in the United States. MethodsWe queried the National Cancer Database and included all patients undergoing anatomic surgical resection for non–small cell lung cancer (2015–2020). The association between demographic and clinical factors and the use of pneumonectomy were investigated. ResultsWho: A total of 128,421 patients were identified, of whom 738 (0.6%) underwent pneumonectomy. Those patients were younger (median 65 vs 68 years, P < .001), more often male (59.9% vs 44.9%, P < .001), more likely to be below median income level (44.2% vs 38.6%, P = .002), and more likely to have lower education indicators (53% vs 48.6%, P = .02) than those who underwent other anatomic resections. Notably, there was a decreasing trend in pneumonectomy use during the study period (0.9% down to 0.4%, P < .001). Where: Patients undergoing pneumonectomy were less likely to live in metropolitan areas (77.9% vs 81.7%, P = .008) and to live closer (<12 miles) to their treating facility (45% vs 49%, P = .02). Regional geographic differences also were identified (P < .001). Why: Patients who underwent pneumonectomy were more likely to have received neoadjuvant therapy (20.6% vs 5.3%, P < .001), to be clinically N (+) (39.3% vs 12.3%, P < .001), and to have more advanced tumors (cT3-4: 46.3% vs 11.3%, P < .001). ConclusionAlthough primarily driven by advanced oncologic features, socioeconomic and geographic factors also were associated independently with the use of pneumonectomy. Standardizing pneumonectomy indications nationwide is crucial to prevent widening outcome gaps for patients with lung cancer.