The number and the locations of transmission lines that are likely to get simultaneously congested is a useful piece of information for power system operation, and activities in the power markets. This study presents, a novel algorithm for estimation of a smaller set of transmission lines that have high probability of being simultaneously congested. To this end, first, the maximum number of simultaneously congested lines is investigated. Then, the algorithm and the corresponded criteria are developed to identify such a smaller group of lines. The algorithm is developed based on two mathematical methods of operation research, which are modified with respect to the features of optimal power flow problem. Moreover, using the insights obtained from the study of the characteristics of frequently congested lines distribution, an index is developed to prioritize the lines with respect to their probability of being congested. The proposed algorithm is also illustrated by simulation of a power market based system.