Martin Marietta Materials mines and sells construction aggregates, including crushed stone, sand and gravel, along with cement and other building materials used in road construction, infrastructure projects and residential and commercial building. Aggregates are heavy, low-value-per-ton materials that are costly to transport long distances, so Martin Marietta's business is built around a network of quarries positioned close to the markets they serve, similar to its main competitor Vulcan Materials. The company's products are used heavily in public infrastructure projects like highways and bridges, giving it meaningful exposure to government infrastructure spending in addition to private construction activity. Martin Marietta's revenue and profitability are closely tied to overall construction activity, which tends to be sensitive to interest rates and economic cycles, though public infrastructure spending provides a somewhat more stable demand base.