From USDA
Commercial-sized farms often require more management and labor than an individual can provide. Additional operators can offer these and other resources, such as capital or farmland. Having a secondary operator may also provide a successor when an older principal operator phases out of farming. In 2015, 39 percent of all U.S. farms (811,000 farms) had secondary operators.
Because nearly all farms are family-owned, family members often serve as secondary operators; nearly two-thirds of all secondary operators were spouses of principal operators. Multiple-operator farms are most prevalent among nonfamily farms, accounting for 85 percent of that group. Some multiple-operator farms are also run by multiple generations.
About 6 percent of all farms (and 16 percent of all multiple-operator farms) were multiple-generation farms, with at least 20 years’ difference between the ages of the oldest and youngest operators. Very large family farms had the highest share of operators from multiple generations: about 28 percent of these farms. This chart appears in the topic page for Farm Structure and Organization, updated December 2016.
Source:usda.gov