Cast iron columns were used extensively in building construction in the United States beginning in the early 1800s and continuing until about the year 1900, when cast iron was supplanted by structural steel. Many structures from this era still exist and are presently being restored or renovated. Little guidance, other than building codes from around the turn of the century, is available to the contemporary engineer charged with assessing the load capacity of cast iron columns. Published material on the historic material properties of cast iron are reviewed, including historic formulae for the ultimate strength and permissible loads for cast iron columns. Results of load tests on cast iron columns carried out during the 1880s and 1890s are summarized and reevaluated. The historic data indicate that the load-bearing capacity of full-scale cast iron columns is not strongly dependent on the column slenderness ratio, L/r. The literature reporting the test results indicates that failure in several columns occurred along planes located at 45° from the longitudinal axis, suggesting that failure was by a shearing mechanism. Or, as in the case of concrete, failure is by the principal tension exceeding the tensile capacity of the material. The quality of cast iron columns was found to be highly variable, indicating that conservative reliability factors (factors of safety) should be used. Capacity formulae for cast iron columns are presented for both allowable stress design and load and resistance factor design.