Over the years there have been attempts to count and report the quantity of horses that exist in the United States. Up until the early 1920's horses and mules were economically an important commodity within the USA economy. However, with the invention of the car, trucks and tractors the need for horses declined rapidly. My research indicates that possibly the census taken in the late 1800's through the 1920's were possibly more accurate than those taken at later dates. The reason I have come to this conclusion is that as there economic value declined the horse became more of a companion animal. Plus at about the same time personal income taxes were introduced. Horse people being the independent lot that they are were reluctant to accurately report their ownership because it was felt the government would find a way to tax horses and the equipment that is used in connection with them. In fact that has been done in some ways in certain states. If you were to conduct in depth research of the population of horses at given times over the past 150 years you would note that there are a number of different figures given by different organizations. However, you will see that there is a trend that runs throughout all the reporting which show a dramatic decline of horses, Mules and draft horses between 1915 and 1949. This decline continued until the late 1950's at which time the population began to increase to it's current population of about 6.9 million. The following information represent averages of different groups that have conducted research.
1867=8,000,000 1900=21,531,635 1915=21,500,000 1920=25,199,522 1930=18,885,856 1935=16,676,000 1940=13,931,531 1945=11,629,000 1950=7,604,000 1955=4,309,000 1960=3,089,000 1965=6,150,000 1968= 6,675,000
The current (2010) estimation of 6,900,000 horses is most likely a bit high do to current economic conditions and recently passed rules regarding the slaughter of horses.
Some of the above statistics came from the following sources:
1950 Census of Agriculture pp 385, 387. Agriculture Statistics 1952 p. 455, 631. Census of Agriculture 1950, p. 204, 398. Agriculture Statistics, 1960 p. 370, 449. Agriculture Statistics 1968, p. 441