Weathering steels ASTM A 242-Type 1 and ASTM A 588-Grade B and steels with 0.21 and 0.021% copper are tested for atmospheric corrosion resistance in marine, rural, and industrial environments. The 16-year atmospheric exposure test results obey well the kinetic equations of the form C = At^B, where C is the corrosion loss, t is time, and A and B are constants. The corrosion resistance of steels is compared on the basis of times required to achieve a 250 μm thickness loss calculated using the rate equations. In these environments, weathering steel ASTM A 242 is at least 16 times more corrosion resistant than the 0.021% copper steel and at least four times more corrosion resistant than the 0.21% copper steel. Similarly, weathering steel ASTM A 588 is about eight times more durable than the 0.021% copper steel and at least two times more durable than the 0.21% copper steel.