“A rising tide lifts all boats”.  When economic progress is steady, or at least not interrupted for too long, this saying seems to hold true.   When everyone benefits from progress, people invest their effort into getting ahead.  Today we face the greatest economic disruption in 75 years.  Without a clear path forward, people of all political views are turning their thoughts enviously towards the boats others.  International trade, labor, spending, health care and tax policies are all being reviewed through the lens of protecting current advantages or redistributing funds.

The classic focus of redistribution is on the “rich” and the “poor”.  Bankers and corporate executives have lost the “entrepreneurial” and “value added” shields of the last 30 years.  Citizens are now concerned about the distribution of income and are willing to consider tax and regulatory changes that would have been unthinkable a decade ago.

The share of income captured by the top 1% of earners receives the most attention.  From 1917-1941, through boom, bust and preparation for war, the top 1% earned 15% of all income.  This changed dramatically during WWII and afterwards, leading to a 35 year period from 1953-1987, where income at the top was cut in half, with 8% of the total going to the top 1%.  Top 1% income grew rapidly in the late 1980’s, reaching 13% and then 15% by 1999 and 17% by 2007. 

The spread of income within the center of the population has also broadened in the last 40 years.  In real 2007 dollars, average household income has increased 30% since 1967, from $40,000 to $52,000 per year.  Families at the 20^th percentile have also seen a 30% increase, rising from $17,000 to $22,000 per year.  The dollar and percentage growth at the higher percentiles has been much greater.  Households at the 80^th percentile have gained 55%, with incomes rising from $67,000 to $104,000.  Those at the 90^th percentile have gained 66%, boosting incomes from $85,000 to $141,000.

There is no “natural” or “optimal” distribution of income.  The US has historically had a greater concentration of wealth or income than other economically advanced nations.  As shown by the top 1%, the concentration can change dramatically through time.  However, most economists agree that there is a level of marginal taxation on income, wealth, dividends and capital gains that significantly reduces incentives for hours worked, innovation, risk taking and entrepreneurship.  

Small changes to the taxation and incentive structure of the US economy are not likely to cause too much damage.  Significant tax increases could do significant short-term and long-term damage to the economy and to those at the lower end of the economic pyramid who depend upon the rising tide to lift their boats in the long run.