The Metro-North Danbury Branch is the almost-be mainline branch of the New Haven Line. The 24 mile line is single tracked with passing sidings, with most service provided by shuttle trains to and from South Norwalk (some shuttle train trips are extended to Stamford) using two to three Shoreliner coaches and a Brookfield BL20GH Locomotive, these shuttle trains run roughly every two hours. During rush hours there are an additional 4 through trains to and from Grand Central, these trains use about 8 Shoreliner Cars and a P32AC-DM Dual Mode locomotive (due to the COVID-19 pandemic this is down to one rush hours through train). The line used by significantly longer with service extending all the way to Canaan, Connecticut until the 1970s. Today extensions have been discussed but not funded (Study) to extend the branch 14 miles north to New Milford, Connecticut. There has also been various talk but no funding to re-electrify the rail line, which was previously electrified between 1925 and 1961. Today all the stations on the line have been rebuilt to have high platforms, or in the case of Merritt 7, funding has been identified to rebuild the station to have a high-level platform.