Final answer:
A large shopping center described in the question, due to its size and composition of national chain stores, is known as a regional shopping mall.
Step-by-step explanation:
A shopping center that ranges from 300,000 square feet to in excess of 1 million square feet and comprises mostly of large national chain stores is commonly referred to as a regional shopping mall or simply a mall. These extensive retail complexes offer a variety of stores and amenities designed to serve a large geographic area and are a significant part of retail distribution in modern cities, drawing in consumers with their convenient one-stop shopping experience. Comparable to historical department stores like Wanamaker's, Selfridge's, and Macy's, regional malls bring together many such large stores under one roof, but on a significantly larger scale.