In addition to the low costs, the US total market index funds offer broad diversification. While asset allocation “experts” will say that you need a separate asset class sleeve for US Large, Mid, and Small Cap stocks in your asset allocation approach. The reality is Harry Markowitz, Nobel laureate for Modern Portfolio Theory, said unless you have a clear return expectation about each distinct asset class and/or the asset classes are not highly correlated then it’s not appropriate to separate out the asset classes. If you need proof then read his paper, Portfolio Selection. The specific advantage of the US total stock market index fund is that it is heavily weighted by mega/large US companies that have a global reach. In fact, 40% of mega/large US company sales are in international markets. There is your international allocation.