The Dow was designed for easy calculation before computers. And it's pretty correlated to the S&P 500 anyway. In theory, price weighting is a poor way to index

The Dow was designed for easy calculation before computers. And it's pretty correlated to the S&P 500 anyway. In theory, price weighting is a poor way to index, but look at it from the other side of the coin - if you choose 30 stocks, from all sectors, how likely is it that you'll get a different return from the market even if you try? Not very. It's only relatively recently that it became popular to never split and let stock prices grow without limit, too. If the prices are mostly in a small range, then the index is similar to an equal weighted one.