• In the early days of the oil boom, Tulsa’s prosperity was threatened by the limited availability of capital funding. Local bankers, who understood cattle and agriculture better than oil exploration, were not inclined to write large loans to wildcatters with little more than big dreams and a high tolerance for risk. Well-established and well-funded oil empires from the east coast were pushing hard to exploit each new discovery within the vast Mid-Continent oil field. If they were able to control Oklahoma’s energy economy, both profit and power would be taken back east, leaving Tulsa a rough frontier town used for organizing labor and equipment in the oil fields—not a professional center of exploration, wealth and power.
  • Realizing the need for a local financial institution powerful enough to stem the tide of eastern influence, an aggressive and crafty young oilman named Harry Sinclair organized a group of investors to establish a true “oilman’s bank.” Opened in 1910, the Exchange National Bank started modestly. But with the help of his brother, E.W. Sinclair, both the bank and Tulsa prospered. The bank marked its success by building an opulent new edifice on the southwest corner of 3rd & Boston in 1917. At the time, Tulsa was the nation’s fast growing city. Under the direction of President J.J. McGraw, so much wealth poured through the bank that the building underwent two dramatic expansions by 1928.

  • The Exchange National Bank nearly folded during the Great Depression. It survived through generous infusions of personal wealth by its board of directors until 1933 when it was reorganized into the National Bank of Tulsa. For the next 42 years, Tulsans knew the beloved structure simply as the ”NBT Building.” Then, in 1975, the bank again changed its name to become the Bank of Oklahoma we know today. The following year, both BOK and their largest tenant, the Williams Companies, moved to the new, 52 story BOK Tower. It was at this time that its original home came to be known as the 320 South Boston Building. In 1987, the 320 was acquired by its current caretaker, Bumgarner Asset Management.
  • The 320 is actually a remarkable collection of five separate building projects that evolved over the course of four decades under the guidance of more than six lead architects. The stunning Beaux Arts face of the building, as well as the central tower and cupola, was raised under the supervision of chief architect Oscar Wenderoth of Weary & Alford in Chicago. In 1953 and 1963, two more additions totaling nearly 120,000 square feet were added to the north and west sides. It was Tulsa’s tallest building for nearly 40 years until the 4th National Bank Tower edged it out by a mere 16 feet in 1965. It also held the status as Tulsa’s largest commercial office space until construction of the Williams Center in 1975.




  • Celebrating 100 Years logo and 4th & Boston book


    Celebrating 100 Years logo and 4th & Boston book



  • 1917-2017

    The Bumgarner family is honoring the century mark for the opening of the 320 South Boston Building (1917) and her stalwart sisters, the Kennedy Building (1916) and the Mid-Continent Tower (1918), all of which stand at the intersection of 4th & Boston. Very few of Tulsa’s oil capitol buildings survived the Urban Renewal era of 1965-1975. And unlike many of those that did survive, these three buildings never fell into disuse or abandonment.

    To honor that perseverance, the Bumgarners commissioned the award-winning book, 4th & Boston: Heart of the Magic Empire to tell the story of these three remarkable buildings, the men who built them, and the city that surrounds them. The project was originally intended to be produced strictly as a gift to tenants in these buildings. As the story evolved, however, it became apparent that it would be a shame to restrict distribution to such a small audience. Thus, the decision was made to expand production enough to make a limited number available to the general public.

    4th & Boston: Heart of the Magic Empire 

    Available for purchase in Suite 1130 of the 320 South Boston Building, Suite 500 of the Mid-Continent Tower, on, and many fine local booksellers. - 4th-Boston-Heart-Magic-Empire

    For more information, call (918) 592-1774 or email