Number of Inhabitants, Oregon, 1970
U.S. Census Bureau · 1971
In the story: 6. The emblem outlives the club, 1930–2010.
The volume that supplies 1960 and 1970, including the slowest decade in the series.
PC(1)-A39. Table 6, “Population of Places: 1970 and 1960”, gives Bend 13,710 and 11,936 — 527 people added across the whole of the 1950s, the slowest ten years Bend has recorded.
1970's figure is the strongest point in the series: the same 13,710 appears here and, independently, in the 1990 volume. That agreement is also what validates reading this scan at all.
What this source supplies
Two of the twelve counts in the Story’s series: 11,936 in 1960 and 13,710 in 1970.