How might old-age dependency change in the US over the next three decades?

In industrialised countries, population ageing is one of the central policy issues of present times, particularly insofar as it relates to the debate over pensions and social care costs. Here, I present a few graphs showing how old-age dependency is projected to change in the US over the next few decades. Data are from the US Census Bureau.

The first chart shows the projected increase in what I've called elderly dependency (the population aged over 65 divided by the working-age population) under three different migration scenarios. The second chart shows the projected increase in what I've called very-elderly dependency (the population aged over 85 divided by the working-age population). This chart is an informative accompaniment to the first one given that a disproportionate amount of individuals' lifetime healthcare costs are incurred in the last few years of life. The third chart simply shows the percentage increase in these projected dependency ratios over the time-period in question: elderly dependency is projected to increase by around 50%, while very-elderly dependency is projected to increase by around 100%.

According to the US Social Security website, Americans may be elligible for social security as early as 62 or as late as 70, depending on the circumstances. My reason for choosing age 65 as the cutoff-point for old-age was simply that the US Census Bureau data are aggregated into 5-year age intervals.