Nagareyama is located in the far northwestern corner of Chiba Prefecture, bordered by the Edogawa River to the west.

The Edo River runs north and south along the western border of the city, opposite which is Saitama Prefecture.

As Japan's overall population reached its peak in the early 21st century, Nagareyama's continued growth has been attributed to city policies from 2003 to heavily invest in childcare centers, including a transit service at Nagareyama-centralpark Station where parents can drop off their children on their way to work, with the children then shuttled with buses to daycare centers.

After the Meiji Restoration, Nagareyama Town was created in Inba District, Chiba Prefecture on April 1, 1889 with the establishment of the modern municipalities system.

Nagareyama has a mayor-council form of government with a directly elected mayor and a unicameral city council of 28 members.

In terms of national politics, the city is part of Chiba 7th district of the lower house of the Diet of Japan.