Industries That Resist Change
While some sectors of the American economy have embraced metric units, others remain stubbornly Imperial, creating the patchwork system that exists today. Understanding which industries resist change and why reveals the practical and economic forces that perpetuate the dual system.
Construction and building materials represent perhaps the strongest bastion of Imperial resistance. Lumber is still sold in Imperial dimensions (2x4, 2x6, 4x8 sheets), and these sizes are integral to American building practices. A 2x4 stud isn't actually 2 inches by 4 inches—it's 1.5 by 3.5 inches after drying and planing—but the nominal Imperial sizing system is so embedded in construction practices that changing it would require rebuilding the entire industry's knowledge base.
Electrical systems provide another example. American electrical boxes are sized for Imperial measurements, conduit comes in Imperial diameters, and wire gauges follow the American Wire Gauge system rather than metric standards. Changing would require not just new products but retraining every electrician and updating every building code.
The automotive industry presents a mixed picture that illustrates the complexity of partial conversion. Modern cars use metric nuts and bolts almost exclusively—a victory for standardization and international manufacturing. But engine sizes are still described in liters (metric) or cubic inches (Imperial) depending on tradition and marketing considerations. Tire sizes use a bizarre hybrid: width in millimeters, aspect ratio as a percentage, and wheel diameter in inches (P225/60R16, for example).
HVAC (heating, ventilation, and air conditioning) systems remain stubbornly Imperial in America. Furnaces are rated in BTUs (British Thermal Units), air conditioning capacity is measured in tons (originally based on the cooling power of one ton of ice), and ductwork is sized in inches. The industry argues that conversion would be particularly costly because HVAC systems are precisely engineered, and changing units would require recalculating every component and retraining every technician.
Aviation provides a fascinating case study in selective metric adoption. Modern commercial aircraft are designed in metric units, and international aviation uses metric measurements for technical specifications. But pilots still think in feet for altitude, knots for speed, and nautical miles for distance. Air traffic control systems worldwide use these same Imperial-derived units, creating a global standard that would be expensive and dangerous to change simultaneously across all countries.
The petroleum industry operates in a complex mix of units that reflects its international nature and historical development. Oil is priced per barrel (42 gallons), but pipeline capacities are often measured in cubic meters per day. Gasoline is sold by the gallon in America but by the liter almost everywhere else. Natural gas might be measured in cubic feet, therms, or cubic meters depending on the application and location.
Food and agriculture show similar complexity. Farmers still think in acres and pounds per acre for crop yields, but agricultural research increasingly uses metric units. Livestock weights are quoted in pounds, but feed efficiency might be calculated using metric conversions. Food packaging shows both units, but cooking measurements remain stubbornly Imperial in American kitchens, despite the fact that professional cooking has largely converted to metric for precision and consistency.