The East Ohio Gas Company next set its sights on Cleveland. Progressive mayor Tom L. Johnson considered natural gas a boon to the working people of Cleveland, and the city granted a franchise to the company in June 1902. Gas arrived in Cleveland via the East Ohio Gas Company on January 1, 1903. Elizur Strong, the first president of East Ohio Gas, led the company's efforts to build pipelines to supply gas to consumers in the area. An innovation in pipe-building, hinged sections, allowed the construction of longer and wider pipes.

Making use of the new technique, the company built an 18-inch wide and 118-mile-long main from the Ohio River to Cleveland. Another pipe connected Canton and Cleveland. Martin B. Daly, who had been instrumental in negotiating the Cleveland franchise, succeeded Strong as president of the company in 1906. During his tenure the company expanded into Cleveland's suburbs and began serving major industrial customers in northeastern Ohio.

In 1908, the East Ohio Gas Company absorbed the Mahoning Gas Fuel Company in Youngstown, and built a gas line from Canton to the Youngstown and Warren areas. The company also took over several manufactured gas firms, purchasing the Cleveland Gas Light and Coke Company and People's Gas Light Company in 1910, the Canton Gas Light and Coke Company in 1911, and Akron's Mohican Oil and Gas in 1913. To meet increased demands generated by the integration of those companies' customers into the East Ohio Gas Company, a 20-inch main was constructed from the gas fields of West Virginia.

The company marked two notable milestones as it entered the World War I era. It began publishing a periodical for its 1,900 employees in 1914, and, in 1916, it constructed a six-story office building in Cleveland. When the United States entered the war, 134 company employees joined the service. To meet the need for workers as the number of men in the workforce plummeted, the company began hiring women as tellers and collectors for the first time.

At the end of World War I, the East Ohio Gas Company entered a period of significant change, both within and beyond the company. The company introduced an annuity and benefit plan in 1918. Regulation, first by the state and then, during the Great Depression, by the federal government, became a fact of life for gas companies. Both during and after the war, demand increased and gas supplies from West Virginia diminished, causing gas shortages. Measures such as efforts to make gas appliances safer and more efficient and raising awareness about the importance of conservation sufficed to protect the supply of gas to East Ohio customers until World War II.

During much of the inter-war period, two brothers presided over the East Ohio Gas Company and led the company through its struggles with supply shortages, competition from electricity, increased federal control, and the Great Depression. Ralph W. Gallagher succeeded Martin Daly as company president when he died in 1926.

Gallagher headed the company until 1933, when his brother Charles E. Gallagher took over. Charles Gallagher was president until 1940. Under Gallagher direction, the company managed to weather the depression without a single employee furlough. Charles Gallagher also managed to guide the company through the aftermath of the Public Utility Holding Company Act of 1935, which forced Standard Oil to divest itself of public utilities as subsidiaries. That divestiture resulted in the creation of Consolidated Natural Gas Company (CNG) in 1943 as a holding company for Standard Oil Company's natural gas concerns, including the East Ohio Gas Company.

On the eve of World War II, J. French Robinson assumed the presidency of the company. It was his task to meet growing demands for natural gas by defense industries in northeastern Ohio. Underground storage pools were opened in 1941 and 1942. The company built a 120-mile pipeline across Ohio in 1943 to tap into pipelines that brought southwestern gas into Ohio. In 1944, gas became available from Hope Natural Gas, another CNG company, when a pipeline linked Hope to gas fields in Texas. The East Ohio Gas Company also made tremendous strides in the liquefaction, storage, and regasification of natural gas. Liquefaction and regasification made it possible to reduce the volume of gas by ratio of six hundred to one, which reduced the amount of storage capacity the company needed.

The company built a plant in Cleveland in 1941 for performing the process of liquefaction and regasification. Three tanks were built to hold 60-million cubic feet of gas each. A fourth tank was added in 1943 that held 120 million cubic feet, setting the stage for a historic industrial disaster. Gas escaped from the fourth tank and ignited into a ball of flame that swept a mile-wide area and claimed 129 lives. In the aftermath of the explosion and fire, the company paid $7,000,000 in compensation to injured workers or families of workers killed in the disaster. It also created a scholarship fund for children of employees who perished.

Following World War II, demand for natural gas skyrocketed. The East Ohio Gas Company built four new trunk pipelines in the first five years after the war and added six hundred new workers before 1950. Company growth spurred efforts to modernize and institute a formal training program for new workers.

Despite the expansion of company operations, East Ohio Gas was unable to keep up with the increasing level of demand for natural gas. Severe winters aggravated the problem, prompting a ban on new gas connections and curtailment of industrial usage. Relief came when the federal government sold two interstate pipelines to the Texas Eastern Transmission Corporation in 1947, and the company increased the importation of natural gas from the southwest.

The use of gas from others states gave rise to federal efforts to regulate the company and lengthy legal battles over the issue. Another remedy for gas shortages was the new practice of storing natural gas underground in depleted gas fields, which allowed large volumes of natural gas to be kept in reserve.

William G. Rogers assumed the presidency of East Ohio Gas in 1951, and a new era began. To compete with suppliers of electric power, the company aggressively advertised its gas and gas appliances, adopting uniforms, standardizing the color of their service trucks, and taking advantage of the new medium of television. A TV program promoting natural gas use, Through the Kitchen Window, was telecast from the company office building.

The modern era continued to unfold under the presidency of Robert W. Ramsdell, who took over in 1957, when Rogers became the board chairman. The company moved into a new headquarters in 1959. Computers were introduced for billing work, and professional business management methods replaced tradition in the offices. The structure of the company was reorganized and new departments were created. During the same era, conflicts arose between the company and government regulators.

The company insisted that regulation contributed to gas supply problems, and regulators contended that prices for natural gas must be kept low and consistent. Despite problems with regulation, the company flourished, and industrial sales expanded. Marketing and sales were coupled with new innovations to serve specific consumer needs, such as cogeneration, in which gas is used to produce electricity.

G.J. Tankersley became president of The East Ohio Gas Company in 1966. He also became chairman of the American Gas Association (AGA) in 1971. Tankersley continued to emphasize marketing and sales, but a looming gas shortage increasingly occupied his attention. To help offset the crisis, the company, in partnership with its parent company, Consolidated Natural Gas, revived gas exploration and production in Ohio and West Virginia. It also stressed conservation and included conservation education in its sales efforts.

The height of the crisis came in the mid-1970s, just after Francis Wright became president of the company. The federal government, reacting to the full-fledged energy crisis, placed a moratorium on new gas hookups between 1975 and 1978. Another complication was the severe winters of the period. Dudley Taw inherited the presidency and the crisis in 1975. A result of the energy crisis was increased employee and consumer activism. Employees were concerned about downsizing that resulted from the gas shortage, while consumers were frustrated about the problems with gas supply.

Improving relationships between the East Ohio Gas Company, its employees and its consumers was an important mission for J. Richard Kelso, who became president in 1981. During the 1980s, the company also benefited from advancements in communications, computerization, and pipeline construction.

The East Ohio Gas Company reflected on its history in 1988 when it celebrated its 90th anniversary. It made plans to create a historical center by soliciting historical materials and developing a system of cataloging and preserving them. A company history, The Spirit of Progress: The Story of the East Ohio Gas Company and The People Who Made It was published. In 1998, the company celebrated its centennial by creating a traveling exhibit and turning over its archives to the Ohio Historical Society so that they could be made available to the public at the Youngstown Historical Center of Industry and Labor.

On January 28th, 2000, The East Ohio Gas Company officially became The Dominion East Ohio Gas Company.