This study empirically investigates traffic congestion effects on agglomeration through the lens of firm location decisions. A discrete choice model is applied to examine new establishments’ location choices within the Los Angeles metropolitan area. Employment centers are defined as the choice set to explore the nature and role of intraurban agglomerations. The results show that metro‐wide congestion negatively affects the location choices of firms in the high‐order office‐related activities, while local congestion have positive impacts on those firms’ location decisions. In contrast, firms in production‐related activities are positively influenced by regional congestion but are negatively affected by local congestion levels.