Simple observations on the calculated capital stock value covered under the Navigation functional category are as follows:
- Significant investment in the Navigation functional category occurred from 1936 up until WWII (see "USACE Capital Stock Additions, Navigation" figure). During WWII, annual investments declined significantly for several years. Following WWII, annual investments in this stock generally increased each year through about 1966, when it peaked at slightly over $4.4 billion per year (with dredging) and $3.7 billion per year without dredging.
- Annual investment in the Navigation functional category generally declined after 1966 until about 1984. However, because investment continued to exceed estimated deterioration during this period, the capital stock continued to increase through 1984. Since 1984, investment in the total navigation (with dredging) stock has hovered around $2 billion per year (all values in 2017 dollars), or about $1 billion per year for navigation excluding dredging.
- The value of the total Navigation (with dredging) capital stock peaked in 1991 at about $91 billion. Similarly, Navigation, independent of dredging, peaked in 1993 at about $84 billion. Since 1993, annual deterioration in the estimated capital stock has exceeded investments, resulting in a decreasing capital stock.
- The 2017 USACE total Navigation (with dredging) capital stock value is $76 billion, or approximately what is was in 1971. Similarly, the 2017 USACE Navigation capital stock value, excluding dredging is $66 billion, or about what it was between 1967 and 1968.
The total Navigation (with dredging) capital stock has declined a little over 25% since peaking in 1991 and is currently about 79% of its peak 1991 value.