The idea that agriculture is Michigan's second-largest industry is a piece of conventional wisdom often iterated, in fact, so much that a Google search for "second largest industry" returns Michigan's iterations of the idea. Yet this is false. Agriculture is nowhere near as large as most Michigan industries.
Agriculture, forestry, fishing and hunting combined account for less than 0.7 percent of Michigan's economic production. That's even proportionally less than the U.S. average of 1.1 percent.
A simple look at the numbers from the U.S. Bureau of Economic Analysis shows that there are a number of industries much bigger than growing crops and raising animals. Indeed, most major industrial groups are bigger than agriculture: utilities, construction, durable goods manufacturing, nondurable goods manufacturing, wholesale trade, retail trade, transportation and warehousing, information, real estate, professional and technical services, management of companies and enterprises, health care and social assistance, arts and entertainment, accommodation and food services and government. The only one that didn't quite measure up is private-sector educational services, which is just about as big.
Even including food manufacturing — counting all the pickle factories and cereal shops — accounts for less than 2 percent of all Michigan production. And people generally don't think of Battle Creek when they're counting the corn.
Even looking at a different measure, employment, shows much the same result. All of the agriculture, forestry, fishing and hunting industries provide just 25,500 jobs, which is less than the number of jobs in Royal Oak. Or, in other words, if you selected a Michigander at random, they're more likely to be able to list the weekly specials at Memphis Smoke than the difference between a pig and a hog.
Apart from a suspicion generated from driving across Michigan and observing the immense amount of land being farmed, the myth's source appears to be a study from the Michigan State University Product Center for Agriculture and Natural Resources. But even the study's authors claim that it was never meant to compare across industries. Nonetheless, they state, "The system is likely second only to the automotive industry as a primary production sector." The qualification "primary production" naturally excludes service industries and even secondary production and the "likely" simply means they're not sure.
That's reasonable — all industries are connected and some more so than others. A hypothetical Michigan without agriculture is impossible to measure and hard to imagine.
Of course, every industry is an important part of the state. Agricultural industries produce large amounts of wealth for Michigan residents, and many families depend on it for their livelihoods. And unlike a lot of other industries in this decade, agriculture has been growing. But it's just not up to snuff for the "second largest industry" in the state.