We examine the impact of high voltage overhead electrical transmission lines on the value of agricultural land in Wisconsin and Illinois. Guiding principles are developed. Views of appraisers are considered, along with institutional details of transmission line easements. A literature review reveals how principles have been ignored in the past. A new hedonic model is developed. The estimated impact of the transmission line easements is both statistically significant and substantially larger than has previously been contemplated. It is essentially the same in Wisconsin and Illinois. Consistency across two states suggests that the results are robust.