power center
n. A large, open-air retail mall that consists mostly of big-box stores.
Less than a generation ago, shopping in the Sacramento area was like visiting a small-town chili parlor — the menu had few choices and relied heavily on some old favorites.

Today, the retail landscape is a smorgasbord of major malls, big-box power centers, upscale plazas and discount chains, each vying for the shopping dollars of the region's 1.75 million residents.
—Mark Glover, “Going with the Flow,” Sacramento Bee, March 19, 2000
The most common form of demalling is the conversion of an enclosed mall into a power center, also known as a "big box" center. Unlike traditional malls, which are inward-facing shells that contain many stores, the power center is a row of large stores, each with its own entrance off the street.
—Morris Newman, “In Rise and Fall of Mall, Weaker Ones Get 'Demalled',” Los Angeles Times, December 14, 1999
1986 (earliest)
Because of the center's size, and because of the large number of customers each of these "anchor tenants" is capable of attracting, Cofer is referring to this project as a "power center".
Chain Store Age Executive, September 01, 1986 (OED)
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