The Newtown bypass officially opens today, marking what campaigners call a "momentous occasion".
The 6.3km long route is expected to ease traffic congestion through the town centre by 40-50% according to the Welsh government. Economy and Transport Minister Ken Skates AM said the development will provide a "real step change" for people in the area.
Construction of the bypass began in February 2016 and is opening ahead of schedule.
£46.8 million has been spent during the construction phase, with a further £10.7 million spent on employing people involved in the project.
Montgomeryshire AM Russell George said the opening of the bypass was a "momentous occasion" for mid Wales. The Shadow Minister for Economy and Transport was involved in initial calls for the new route.
In March 2011, over 30 people handed in a 10,000 strong petition to the National Assembly for Wales which called for a Newtown Bypass.