Urban mass transportation research has predominantly focused on the metropolitan scale and population. However, with the growing body of urban literature on global cities and polycentric urban regions, it is timely to assess the rapid transit potential of urban regions comprising multiple cities in close proximity. Rather than relying solely on population size or spatial proximity, this study is based on the premise that high-capacity transit systems are more viable where strong business linkages exist between cities. In the Indian context, rapid transit research has largely concentrated on Tier-I cities, with limited attention to regions beyond these metropolitan areas. This study addresses the gap by focusing on urban clusters formed by Tier-II cities and evaluates their potential for regional rapid transit by assessing intercity firm linkages. However, the firm network is constructed using both Tier-I and Tier-II cities, as Tier-I cities function as key hubs in the national firm network and mediate a large share of intercity linkages. Firm linkages are derived from office location data of advanced producer service firms using the interlocking network model across 96 cities in India, thereby constructing a nationwide intercity business network. The subsequent cluster identification and evaluation focus only on spatially proximate Tier-II cities. Clusters are identified and evaluated in two configurations, city pairs and multi-city corridors. For each cluster, a composite index combines linkage intensity, network centrality, population, and intercity distance to rank clusters. The analysis is intended as a preliminary economic network based assessment of potential rather than system level feasibility. The results indicate that urban clusters with moderate population sizes can rank higher than larger clusters when strong business integration and network embeddedness are present. The findings highlight the importance of economic integration in shaping regional transit potential beyond conventional population-based criteria, informing policymakers in prioritizing capital intensive investments.