Investing isn't easy. Even Warren Buffett counsels that most investors should invest in a low-cost index like the S&P 500. He says that way "you'll be buying into a wonderful industry, which in effect is all of American industry."

But there are, of course, companies whose long-term fortunes differ substantially from the index. In this series, we look at how individual stocks have performed against the broad S&P 500.

Step on up, Norfolk Southern (NYSE: NSC).

Norfolk Southern shares have outperformed the S&P 500 over the last quarter century, with most of the difference occurring in the last few years:

Source: S&P Capital IQ.

Since 1987, shares have returned an average 11% a year, compared with 9.7% a year for the S&P (both include dividends). That difference adds up fast. One thousand dollars invested in the S&P in 1987 would be worth $19,200 today. In Norfolk Southern, it'd be worth $27,900.

Dividends accounted for a lot of those gains. Compounded since 1987, dividends have made up about half of Norfolk Southern's total returns. For the S&P, dividends account for 39% of total returns.

Now have a look at how Norfolk Southern earnings compare with S&P 500 earnings:

Source: S&P Capital IQ.

Some outperformance is evident. Since 1995, earnings per share have increased by an average of 7.6% per year, compared with 6% annual growth for the broader index.

What's that meant for valuations? Norfolk Southern has traded for an average of 22 times earnings since 1987 -- close to the 24 times earnings average of the S&P 500. It's far different today, however. Shares currently trade for about 11 times next year's earnings.

Through it all, shares have been strong performers over the last quarter century.

Of course, the important question is whether that will continue. That's where you come in. Our CAPS community currently ranks Norfolk Southern with a five-star rating (out of five). Do you disagree? Leave your thoughts in the comment section below, or add Norfolk Southern to My Watchlist.