As the 20th century dawned, however, the province's economy again began to expand. Manufacturing gained strength with the construction of textile mills; and in the crucial forestry sector, the sawmills that had dotted inland sections of the province gave way to larger pulp and paper mills. The railway industry, meanwhile, provided for growth and prosperity in the Moncton region. Nevertheless, unemployment remained high throughout the province, and the Great Depression brought another setback. Two influential families, the Irvings and the McCains, emerged from the Depression to begin to modernise and vertically integrate the provincial economy—especially in the vital forestry, food processing, and energy sectors.

The Acadians in northern New Brunswick had long been geographically and linguistically isolated from the more numerous English speakers, who lived in the south of the province. Government services were often not available in French, and the infrastructure in predominantly Francophone areas was noticeably less developed than in the rest of the province; this changed with the election of Premier Louis Robichaud in 1960. He embarked on the ambitious Equal Opportunity Plan, in which education, rural road maintenance, and health care fell under the sole jurisdiction of a provincial government that insisted on equal coverage throughout the province. County councils were abolished, and the rural areas came under direct provincial jurisdiction. The 1969 Official Languages Act made French an official language.