What happened from 72 to 80?
1972 1979 At the end of the 1960s, BSA National saw the underserved communities, primarily in urban areas, and created a new "Urban Emphasis" program. The BSA's modernization was consistent with similar trends in Scouting all over the world starting in the 1960s. Much of these changes could be seen in the 8th edition of the Boy Scout Handbook used from 1972 - 79. The junior leader system, known as the green bar patrol was renamed the Leadership Corps. A significant uniform change in the Boy Scout program was made when BSA dropped the traditional garrison cap and adopted a red beret. The rank requirements were changed such that a scout could earn the First Class rank without ever going camping. A tidal wave of frustration arose among veteran scouters who accused the BSA of taking the outing from Scouting. The change was so drastic and unpopular that by 1976 long-time veteran, and retired, scouter, William Green Bar Bill Hillcourt, began writing the 9th edition of the Boy Scout Handbook to bring back the outdoor camping skills that were omitted in the 8th edition. The Leadership Corps also went back to the green bar patrol system, now referred to as the patrol leaders council. The Urban Emphasis program was the forerunner of the Scoutreach Division of BSA which was created in 1994 to provide service to rural and urban areas and to minority populations.
1973 Total youth membership in all 3 BSA programs (Cub, Boy, Explorer) peaked at 4,852,827. It has been generally declining ever since. Other programs were added after 1973 = Tiger Cubs, Webelos, Varsity, Venture, and Learning for Life. It is difficult to find the membership data for the separate programs since 1975. BSA National tends to combine all 3 Cub programs together and Varsity with Boy Scouts. Then you have the confounding problem when BSA stopped reporting Exploring and Learning for Life membership numbers because they were separated out from the traditional programs in the late 1990s. So, the simplest graph to gain sense of BSAs health would be to look at the youth membership numbers in troops.
Basically, youth membership, in troops only, declined 44% between 1970 and 1980.