The designation can also be applied in some cases to sections of uncontrolled access roads which are deemed strategically important and which will be upgraded in the future to controlled-access.

These highways connect major population centres such as the Halifax Regional Municipality and Cape Breton Regional Municipality with smaller population centres such as Yarmouth, Truro, New Glasgow and Amherst, as well as the neighbouring province of New Brunswick.

The typical naming convention is to add 100 to a route containing a local trunk highway.

A 100-series freeway is roughly equivalent in function to the 400-series highways of Ontario, Autoroutes of Quebec, or the Interstate Highway System of the United States, albeit on a much reduced scale and amount of traffic.

Many of these highways were developed during the 1960s–1990s as political projects and proved detrimental to rural railway service in the province, resulting in many rail line abandonments.