The Ford F-150, shown here in Limited trim, and its Super Duty siblings are America's top-selling pickups. Photo credit: Ford Motor Co.

June was the best month for U.S. auto sales since 2007, and one big factor is the boom in sales of full-sized pickup trucks. Ford (NYSE:F), General Motors (NYSE:GM), and Chrysler all posted big gains in pickup sales last month, and all three gained U.S. market share in the first half of 2013 – the first time that has happened in 20 years.

What's behind the boom? In this video, contributor John Rosevear looks at the economic "perfect storm" that has made for great pickup sales, and at why that's likely to be a big deal when the Detroit automakers report second-quarter earnings later this month.

Fool contributor John Rosevear owns shares of Ford and General Motors. Follow him on Twitter at @jrosevear. The Motley Fool recommends Ford and General Motors. The Motley Fool owns shares of Ford. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.