This paper examines the formation of the Iranian railway workforce in the early twentieth century to demonstrate the importance of transnational connections with Iran’s surrounding world, such as the Caucasus and the Persian Gulf, to understand the process of nation building. Iran was a latecomer to the age of railways. Only in 1938 did the Pahlavi state complete the Trans-Iranian Railway, the first extensive railway in Iran, and the symbol of Pahlavi success in rejuvenating the nation. Yet, because the Railway Organization needed such workers as locomotive drivers, repairers, and various kinds of skilled workers for maintaining and operating the completed sections, the formation of the railway workforce had already begun in the 1920s. Existing scholarship sees railway projects in Iran within the framework of the tensions between railway imperialism and Iranian nationalism. Thus, the Iranian state project of the Trans-Iranian Railway is seen as a triumph of the nationalist regime of Reza Shah Pahlavi. This framework is reflected in brief references to labor formation in the railway industry, which considers only Iran and the “West.” Thus, the narrative starts with the hiring of Western managers and railway engineers as well as the dispatching Iranians to the “West” to study railway-related subjects, particularly during the 1920s. This phase is followed by the establishment of railway schools in Iran by the Pahlavi state, which led to the formation of the indigenous workforce by the time of Reza Shah’s abdication in 1941. This paper demonstrates two ways in which the transnational flow of labor contributed to the formation of the first generation of railway workers in Iran. Firstly, by using mini-biographies of rank-and-file railway workers published in the 1940s, it demonstrates the transnational labor flow between northwestern Iran and Anatolia, the Caucasus, and southern Russia before the establishment of the Pahlavi Dynasty. Secondly, by using archival documents from the British Library in London and from the Majles Library in Tehran, it shows the large presence of Indian and Iraqi railway workers in the 1920s, until that presence dwindled by the late 1940s. Therefore, this paper resituates Iran in multiple regional networks using the case of labor formation in the railway industry and rectifies the historiographical tendency to overemphasize either the nation or the interaction between Iran and the “West” as a framework to understand technological projects.