Wikipedia
M-TAG refers to the first generation of Electronic Toll Collection (ETC) system used in the state of Maryland by the Maryland Transportation Authority (MdTA) from 1999 to 2001. The request for proposal for the system was issued by the authority in 1995.
The contractor awarded the contract for the state of Maryland that developed the M-TAG software was Lockheed Martin IMS Division.
M-TAG / E-ZPass is an electronic toll-collection system available at all MdTA Toll facilities: the Baltimore Harbor Tunnel, the Fort McHenry Tunnel, and the Francis Scott Key Bridge. When it came on line in 1999, the system was known as M-TAG. As of October 2001 the system became reciprocal with the other E-ZPass Toll agencies and Maryland then renamed its system to E-ZPass. At that time the JFK Memorial Highway joined, followed by the William Preston Lane Memorial (Bay) Bridge and the Harry W. Nice Bridge, and the Thomas J. Hatem Bridge was the last to come up in April 2002. E-ZPass allows a customer to drive from North Carolina to Maine and Illinois without stopping to pay tolls. A driver receives a small radio frequency transponder to place on the inside of a vehicle's windshield. Equipment in the toll lanes records the transactions, and trips are automatically deducted from the customer's account.