On a trip to the Midwest this week, U.S. Secretary of Agriculture Tom Vilsack offered some advice to the next presidential administration. As the candidates tour the country and remain largely silent on agriculture and food issues, the Agriculture Department's purview remains important.

"The next agriculture secretary needs to have a very broad understanding of what this department does, who it impacts – and that it has an impact and effect on every single American," Vilsack says, "not just Americans in one part of the country or growing one type of commodity."

Vilsack is the only remaining member of President Obama's original cabinet, and has been at the helm of USDA since 2009. In that time, the department has expanded programs for local foods and farmer's markets, school meals and nutrition, and rural development. He noted that soon the agricultural sector and a new Congress will begin work on the next farm bill, which covers everything from crop safety nets to the food stamp program.

"My hope is that the next Agriculture secretary understands the importance of diversity," Vilsack says, "in terms of size of operations, in terms of crops, and so forth, so they can continue to speak to a broader audience."

Though the Agriculture Department does oversee billions in programs for large conventional farms, Vilsack pointed out that everybody is impacted by food and agriculture policy, regardless of where they live or whether they feel a direct connection to farming. But he also recognized that the department needs to reach out to all types of farmers, regardless of geography or commodity. And those within the sector also need to advocate for themselves.

"I think agriculture, and those in agriculture, have to continue to do what they have started to do, which is to speak to the other 99 percent of Americans that [don't] farm," Vilsack says.

As an example, Vilsack said agriculture did better than many other industries in making clear its support for the Trans-Pacific Partnership, a 12-member trade deal that the Obama administration supports but that is languishing in the United States in part because both major party presidential candidates oppose it.

The secretary also encouraged his successor to promote a "message of appreciation and understanding" to rural America, including farmers.

"Every single one of us that's not a farmer is not a farmer because we've delegated responsibility of feeding our families to people we don't even know," Vilsack says. "And we gladly do it. And then we walk out of a grocery store and we have more flexibility with our paycheck than anybody else in the world."

He says other countries like China envy our food security.

Vilsack is the longest-serving Secretary of Agriculture since 1969.