The following commentary comes from an independent investor or market observer as part of TheStreet's guest contributor program, which is separate from the company's news coverage.NEW YORK ( ETF Expert) -- Could it be that the U.S. economy is actually accelerating? Is it possible that the drama in Greece is nearing a resolution? Well, stock investors seem to think so. The S&P 500 is inching closer to a 52-week high reached last April, while the Dow is approaching a price that we haven't seen in four years. On the flip side, crude oil prices have rocketed more than 12% over the prior six weeks. It's certainly within the realm of imagination that with the rising prices of petroleum-based products (e.g., diesel, gasoline, jet fuel, etc.), transporters may transport less. Equally disconcerting, consumers may travel less. And the fragile U.S. economy might find itself in dire straits yet again. Let's examine United States Gasoline ( UGA) for clues. The last time that UGA was firing on all cylinders was at the end of April, 2011. Ironically , gasoline prices began to tank at the same time that the S&P 500 came off its loftiest perch.