I-95 enters Connecticut at its crossing of the Byram River into the town of Greenwich in Fairfield County, where it continues southwest into New York as the New England Thruway. Upon entering Connecticut, the highway is a six-lane freeway known as the Connecticut Turnpike. The road is paralleled by Metro-North Railroad's New Haven Line to the northwest, which also carries Amtrak's Northeast Corridor, which it follows for much of its length throughout the state. I-95 heads northeast, passing through the affluent suburban development of the Gold Coast of southwestern Fairfield County and reaching a weigh station in the northbound direction, before turning east-northeast and passing south of downtown Greenwich. The road then heads into the neighborhood of Cos Cob before it crosses over the New Haven Line and the Mianus River, on the Mianus River Bridge. Past the river, I-95 comes to a trumpet interchange which provides access to US 1 between the neighborhoods Riverside and Old Greenwich.