McGregor, first known as McGregor Springs, is an incorporated town sixteen miles southwest of Waco on U.S. Highway 84 in western McLennan County. It was established in 1882 at the intersection of the Gulf, Colorado and Santa Fe and the Texas and St. Louis railways. The new town was named McGregor Springs in honor of Gregor Carmichael McGregor, a doctor who gave the railroad right-of-way to cross his land. Advertisements for excursion trains to the prospective city appeared in Texas newspapers, and on September 7, 1882, a state land commissioner sold lots at auction from the back of a railroad flatcar. Because of its favorable location, McGregor drew much of its early population and several businesses from nearby small communities like Banks and Comanche Springs in McLennan County and Eagle Springs in Coryell County. The post office at Banks was transferred to McGregor in October 1882, keeping Thomas H. Baker as postmaster. By 1884 McGregor had a wide variety of businesses, a weekly newspaper, a school, and several hundred residents. The town adopted a city charter in November 1886. The next decade or so brought the addition of two hotels, a national bank, a washing-machine factory, a tannery, a cottonseed oil mill, and an artesian waterworks. The census of 1890 gave the population of McGregor as 774, but other estimates for the same time period were as high as 1,500.
McGregor continued to prosper in the early 1900s as the commercial center and shipping point for much of western McLennan County. The population was listed as 1,864 in 1910 and 2,081 in 1920. Although the number of residents and businesses fell slightly during the Great Depression, the community weathered this period well. The local economy received a significant boost in 1942, when the United States Army announced plans to build the Bluebonnet Ordnance Plant on 18,000 acres just southwest of town. As a result of this new industry, the population of McGregor tripled in three months to more than 6,000. After World War II it fell back to about 2,000, and the ordnance plant was converted to a variety of peacetime industries, such as stove and furniture manufacturing. In the 1950s part of the old plant was converted to manufacturing rocket engines, solid propellants, and gas generators. Much of the rest of the land was either sold to individuals or given to Texas A&M University for the development of an experimental farm and research center. The wide variety of job opportunities attracted new residents to McGregor, bringing its total population to 2,664 in 1952 and 4,642 in 1961. The population was 4,289 in 1978 and 4,683 in 1990. In 2000 the population was listed as 6,563.