Canadian manufacturers say business conditions improved again in September.
Since 2012, clients have been able to benefit from the U.S. recovery.
Ontario's economy is poised to benefit from U.S. growth and a weaker Canadian dollar in the next two years.
Adjusted for seasonal influences, the index registered 54.8 in August, up from 54.3 in July and comfortably above the neutral 50.0 value.
The rise was driven by faster rises in output, new orders and employment at the start of the third quarter, says RBC PMI.
For years, Canada's manufacturers have been struggling.
Statistics Canada says manufacturing sales rose 1.6% in May to $51.6 billion, the fourth increase in five months.
The RBC Canadian Manufacturing Purchasing Managers' Index indicates a rebound in the manufacturing sector in June, as output and new business growth picked up to the strongest recorded so far in 2014.