Had not its main body moved to the inter-mountain west, the Church would not have grown and prospered that way it did. In order to achieve an economically self-sustaining societal critical mass in an inhospitable environment, Brigham Young, the industrialist, needed a large number of workers possessing post-agrarian vocational skills and the motivation and financial wherewithal to pick up and relocate. Uniquely able to satisfy that need was post-industrial-revolution Great Britain, which provided about three-quarters of the 60,000 to 70,000 Saints who had immigrated to the Salt Lake Valley by 1868.