The plaza and a number of its surrounding buildings are a National Historic Landmark District, significant for its role in the transfers of power that brought first the original New Mexico Territory and later the Gadsden Purchase into United States control.

The Mesilla Plaza was the site of an official flag-raising ceremony on November 18, 1854, confirming United States sovereignty over the area.

On August 27, 1871, Democrats held a large political rally in the plaza for their candidate for territorial delegate to the United States Congress.

Soldiers from nearby Fort Selden stationed in the town to stop any violence had left earlier when it appeared the rallies were peaceful.

The plaza itself, originally an open dirt area, is now lined by brick sidewalks and is grassy, and sports a bandstand built in the 1970s.