The subsequent years saw Jinja grow economically with expansion of commercial activities that accelerated considerably. Later Jinja became a focus of modern manufacturing industry and the seat of Uganda 's leading industrial concerns. The basis for these developments was the decision taken in 1947 to proceed with the construction of the Owen Falls Dam. The completion of the Owen Falls Dam marked a major turning point in the economic development of the town and the country at large.
Like many of the municipalities in Uganda according to the Official Gazette of the East Africa and Uganda Protectorate Vol. VIII No 161 Jinja was designated as a township on the 26th of June 1906. About 50 years later in January 1957 Jinja was pronounced and declared a municipality.
"Jinja" is a Luganda word meaning "stone". It is suggested that Jinja derived its name from either the rocks of the submerged falls of Rippon and Owen or, more probably to a sacrificial stone on a hilltop overlooking the town not very far from the today District Director of Health Services offices.