Conventional wisdom says that growth in the America container-board market is heavily tied to the health of the U.S. economy, and a company's overall success is directly proportional to the size of the operation. But Packaging Corporation of America (NYSE: PKG), one of the most profitable of all of the U.S. container-board companies, defies both of these notions.

PCA is a relatively small operation, when compared to its rivals. But the company is successful because of two fundamental strengths: a low debt load and flexibility of both fuel and fiber. The low overhead of a company operating with relatively little debt is easy to understand, but there are significant cost savings to be gained in this market as well by having the ability to adapt production to whichever raw materials are cheapest and most readily available.

PCA's flexibility also gives it an advantage over the competition when it comes to the international markets. Other countries, especially in Asia, require different products than the U.S. market does, and PCA's ability to adjust its production process to meet this foreign demand with relatively little change in expense leaves the company able offset any instability in the U.S. economy with income from foreign markets (especially China).