Background This study aimed to clarify differences in the prognostic impact of tumor spread through air spaces (STAS) in lobectomy versus sublobar resection (SR). The study also investigated the frequency and significance of STAS in residual lung segments. Methods This study identified 752 patients with p-stage 1A non-small cell lung cancer (NSCLC) from 2010 to 2012. Recurrence-free survival (RFS) and overall survival (OS) were compared. For proactive simulation of SR, 100 consecutive lobectomy specimens of p-stage 1A NSCLC were selected. Results The study found STAS in 182 (28.7%) of 634 lobectomy cases and 43 (36.4%) of 118 SR cases. Multivariable analysis showed that STAS was not a prognostic factor in the lobectomy group, but showed a significantly worse prognostic effect for the SR group (RFS, P  < 0.001; OS, P  < 0.001). In 9 of 100 simulated cases, STAS occurred in residual lung segments. The patients with T1c category disease had a significantly increased risk for the development of STAS in residual lung segments ( P  = 0.033). Conclusions For patients with p-stage 1A lung cancer who have undergone SR, STAS is a prognostic indicator of poor outcomes. The presence of STAS does occasionally exist in the residual lung segments.