BISMARCK, ND (AP).- The majority owner of an oil company that has been drilling for crude in western North Dakota has donated $1.8 million to help finance construction of a major expansion to North Dakota’s Heritage Center. Harold Hamm’s contribution should allow construction to begin this summer. The $51.7 million expansion will double the size of the museum on the state Capitol grounds and add a theater, display galleries, new glass entrance and cafe. The building first opened in 1981. Hamm is chief executive and the controlling stockholder of Continental Resources Inc. of Enid, Okla. He owns more than 70 percent of Continental’s stock, according to the company’s most recent annual report. At current market prices, his stake is worth more than $5 billion.