U.S. Sen. Dick Durbin (D-IL) and U.S. House Democrats from Illinois are concerned over the proposed merger of two rail operators in the state, Canadian Pacific Railway (CP) and Norfolk Southern Corporation (NS).

The federal lawmakers sent a letter Monday to the Surface Transportation Board, the agency that considers railroad industry mergers and acquisitions, requesting a careful review of possible negative effects of the proposed merger on Chicago, the rail network in Illinois and the economy.

"We are writing to you regarding Canadian Pacific Railway's proposal to acquire Norfolk Southern Corporation, a merger that could have significant implications to the freight network in Illinois and this country," the letter reads. "We are concerned about the effects of the proposed CP-NS merger on Chicago. We urge you to carefully review any plans submitted to the STB, and consider the potential negative impact of the proposal with respect to building a more efficient freight network in Chicago... and comprehensively examine the economic effects of such a consolidation on local industries and jobs in the Chicago region."

The letter was signed by Durbin and U.S. Reps. Bobby Rush (D-IL,1), Dan Lipinski (D-IL,3), Luis Gutierrez (D-IL,4), Mike Quigley (D-IL,5), Danny Davis (D-IL,7), Tammy Duckworth (D-IL,8), Jan Schakowsky (D-IL,9), Bill Foster (D-IL,11) and Cheri Bustos (D-IL,17).