What phenomenon occurs when urban areas expand into the surrounding suburban regions?

Urban sprawl refers to the phenomenon where urban areas extend into the surrounding suburban and rural regions, often resulting in the development of low-density residential and commercial properties. This expansion tends to occur as cities grow to accommodate population increases and the demand for housing, leading to the spreading out of cities into previously undeveloped land.

This process can contribute to various issues, such as increased reliance on automobiles, longer commutes, and environmental concerns related to the loss of green spaces and wildlife habitats. Urban sprawl contrasts with more sustainable urban planning strategies that aim to create denser, mixed-use developments and minimize the environmental footprint of cities.

In contrast, the other options refer to different concepts in urban planning. Suburban encroachment often emphasizes the impacts of urban growth on suburban areas rather than the expansion itself. Smart growth focuses on sustainable urban planning strategies that promote denser, more efficient land use. Greenfield development refers specifically to building on undeveloped land, often in the context of new projects, but does not encapsulate the broader concept of urban areas expanding.