partido (county) on the western periphery of Gran (Greater) Buenos Aires, Argentina. The settlement of Moreno was founded by Amancio Alcorta in 1860. Five years later the county was established. In 1864 the western railroad from Buenos Aires was extended through Moreno toward Luján.

Moreno experienced rapid population growth in the 1960s and '70s, but its population density is still less than most other counties in Gran Buenos Aires. Pop. (2001) 379,300.