[4] In 1956, he was hired by United Press to manage its Jefferson City, Missouri, news bureau.

Sebree renamed the business "Interurban Press" and, after adding a partner, Jim Walker (as vice president), expanded the company's output.

[10] Under Mac Sebree's ownership, Interurban acquired the monthly railfan-oriented magazines, Pacific RailNews (PRN) and Passenger Train Journal, and the bimonthly Private Varnish.

He followed with great interest the revival in the 1980s of streetcars as a significant public transit mode in North America, modernized as "light rail", telling a Los Angeles Times reporter in a 1983 interview, "The United States let a tremendous national asset go to waste when it junked its trolley systems, but the further the trolleys fade into the past, the larger the number of people who would like to have them back.

[13] In 1993, Sebree retired from full-time work, sold Interurban Press to Pentrex and moved from southern California to Vancouver, Washington.

In 2005, Sebree donated $20,000 to the Railway & Locomotive Historical Society (based in Sacramento, California), to establish a trust fund to provide permanent support for publication of the organization's longtime journal, Railroad History.

[18] In 2008 Sebree donated $10,000, and pledged $90,000 more, to the Orange Empire Railway Museum to support the construction of a permanent library and archive building.