From the 4 companies listed, Walmart is the company with the most U.S. employees. It has over 1.4 million employees working in the United States. It is an American multinational retail corporation that operates a chain of hypermarkets, discount department stores and grocery stores. It is headquartered in Bentonville, Arkansas and was founded by Sam Walton in 1962.

Target Corporation is the second-largest discount retailer in the United States, behind Walmart. It was founded by George Dayton and is headquartered in Minneapolis, Minnesota. It has over U.S. 347,000 employees.

McDonald's is the world's largest chain of hamburger fast food restaurants, serving around 68 million customers daily in 119 countries across more than 36,000 outlets. Founded in the United States in 1940, the company began as a barbecue restaurant operated by Richard and Maurice McDonald. In 1948, they reorganized their business as a hamburger stand using production line principles. Today, in the U.S., McDonald's has over 500,000 employees who work for franchises.

Concerning Home Depot, it is an American retailer of home improvement and construction products. Plus, it provides services to customers. It is headquartered at the Atlanta Store Support Center in Cobb County, Georgia, in Greater Atlanta. In the U.S., more than 371,000 employees are working for the company.

More Info: en.wikipedia.org