Demographic growth was relatively slow. During this period, Rosario was a small settlement and a stop in the way from Santa Fe City to Buenos Aires. In 1823 it was elevated to the category of "village" (Ilustre y Fiel Villa del Rosario). Charles Darwin travelled through the area in 1832 and described Rosario as "a large town" with about 2,000 residents. In 1841 its port was shut off to foreign trade by a decree of the caudillo and Governor of Buenos Aires, Juan Manuel de Rosaswhich banned navigation of the Paraná and the Paraguay rivers to non-Argentine vessels.
On 25 December 1851, a small group of locals and the military guard of the city declared their support for the rival caudillo Justo José de Urquiza. As a reward for their participation in the Battle of Caseros, triumphant Urquiza wrote to the governor of Santa Fe on 9 June 1852 asking for Rosario to be granted city status. Governor Domingo Crespo justified the request at the provincial legislative body, marking the geographically strategic position of the town for national and international trade, and on 5 August Rosario was formally declared a city.
Urquiza opened up the river for free international trade. The city's economy and population expanded at an accelerated rate. By 1880, Rosario had become the first export outlet of Argentina. By 1887 it had about 50,000 inhabitants, of which 40% were immigrants, who brought new ideas from Europe and started turning Rosario into a politically progressive city (contrasting with the more conservative, aristocratic Santa Fe).
During part of the second half of the 19th century, there was a movement promoting that the city of Rosario become the capital of the republic. Ovidio Lagos, founder of the oldest Argentine newspaper, La Capital, was one of the strongest defenders of this idea (one of the main avenues in Rosario now carries his name). Rosario was indeed declared the federal capital in three occasions, but each time the law received a veto
