2,000 inhabitants, Junín ceases to be categorized as a "fort," and its first municipal master plan was laid out in 1865.
The 1880 arrival of the Central Argentine Railway and that of the Buenos Aires and Pacific Railway (B.A.& P.) in 1884 led to the town's rapid growth. The National Bank of Argentina had opened a branch there in 1892 and by the 1895 census, Junín was home to over 12,000. The town largest employer by then was the B.A.& P.'s rail equipment factory, which employed over 1,600. The City Hall was completed in 1904 and Junín was declared a "city," in 1906.
Junín's steady development over the subsequent decades and setting amid lakes made it a well-known regional tourist destination. A hunt club was established in 1938, and a fishermen's pier and club on Lake El Carpicho, in 1942. The Aero Club Junín (1940) became well-known following the IX International Gliding Competition, in 1963, and the nearby Borchex Municipal Park and Lake Gómez both have become popular weekend destinations since the 1960s; Lake Gómez attracted around 350,000 visitors during the 2006-07 summer season. Nearby Estancia La Oriental has attracted growing rural tourism to the area, as well.
The city is home to an important Municipal Historical Museum, probably best known for its paleontology hall and its wooly mammothfossils, and the Ángel María de Rosa Municipal Museum of Art (1944). In a bid to further diversify the city's economy, an industrial park was authhorized north of the city in 1995, and a racetrack, the Autódromo Eusebio Marcilla, was opened in 2003. The closure of much of Argentina's passenger rail service during the 1990s was partly offset in Junín in part by the purchase of local rail facilities by América Latina Logística, a São Paulo-based rail transport provider operating largely in Argentina, as well as by establishment of the Junín Railworks Cooperative.
The city features numerous cinemas, as well as prominent stage
