I examined data from the US Census of Agriculture on beef farms by farm size, which spans from 1997 to 2012.
Most beef farms are small, but their number seems to be decreasing. All of these farm counts have decreased since 1997, although the amount of farms with 1-9 cattle has increased since 2002. Since a definition of cattle factory farms focuses on cattle in feed lots, I do not think that this data is necessarily informative of cattle in factory farms.
The distribution of cattle shows that most cattle are on medium sized farms. Surprisingly, there are fewer cows raised for beef in the United States in 2012 than there were in 1997. This result is possible explained through the decreasing per capita consumption of beef in the United States.
While the similar data set on hog farms shows a dramatic trend of industrialization, the beef cattle data does not tell the same story. Up next: dairy cattle.
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The code used to generate these graphs is on GitHub.