A significant development took place in 1902-1904 after the General Mining Association sold its holdings to the Nova Scotia Steel and Coal Company, A blast furnace was built at Sydney Mines, as well as four batteries of coke ovens, and a 50-ton-per-hour coal washery at the colliery.
The construction of a Steel Plant in Sydney Mines began in 1902 and went into operation three years later, which at that time was considered to be the most efficient and modern in Canada. The Hydraulic Fluid Steel Compression Plant in Sydney Mines was the first ever installed in Canada.
A period of prosperity followed. In the first nine years of the 20th century, twenty miles of new streets were constructed, water and electric lighting systems were erected and railway accommodation was provided.
This was the beginning of the glory years in the town as it began to build bigger buildings, more elaborate houses, schools, churches, hotels and of course with growth, came more people.