US gas prices have reached a record of $4.05 and energy wonks now say that US gas prices could rise to a national average of $4.25 a gallon by the Fourth of July and are unlikely to fall as long as oil prices keep surging.

Jennifer Yousfi explains how US gas prices could keep on rising…

If oil stays near $140 per barrel, gas prices could easily top $4.75 a gallon by the Fourth of July holiday, Mark Zandi, chief economist at Moody’s Economy.com (MCO), said in a recent research note.

And while the thought of gas at almost $5 per gallon is distressing enough, Money Morning’s Investment Director Keith Fitz-Gerald thinks gas prices could go even higher. In fact, U.S. motorists could easily be looking at $7 a gallon gasoline within just two years. And that could have a disastrous impact on the U.S. economy.

“The bottom line is that the effect on the economy is going to be a lot worse than anyone’s talking about right now,” said Fitz-Gerald, a longtime energy bull who recently boosted his oil-price projection to $225 a barrel. “The bottom line is this: Until someone develops a truly [interchangeable] alternative for oil and gasoline - something that works the same, costs the same and is just as effective - Americans are just going to have to face the fact that over time they’re going to pay more.”

By fixating on near-term prices, and near-term fallout, Fitz-Gerald says that investors and economists alike are missing the bigger point: Long-term - or at least until a true replacement for oil is found - the U.S. economy is going to be badly stung, and U.S. consumers who don’t take steps to protect themselves are looking at a markedly reduced standard of living.

Moody’s Economy.com’s Mark Zandi agrees.

“Unless oil prices soon recede and Washington changes its views and acts to shore up the housing market and broader economy, the outlook for 2009 will weaken further in coming months,” Zandi said.

Zandi added that the U.S. Federal Reserve “will sacrifice near-term growth for the sake of stable prices and the economy’s longer-term prospects” and that the high cost of oil will prevent any further interest rate cuts.

But don’t look for gas prices to move up in a straight line to $5, $6 and $7 a gallon, Fitz-Gerald says. Prices will continue to fluctuate. There will be rallies, and retrenchments, as is the case with the price of any commodity.

But prices will rise, as there is still no truly “fungible” - interchangeable - replacement for petroleum. That’s what’s needed, Fitz-Gerald says.

In the interim, investors should: be “long” on oil and other commodities; have alternative-energy-related investments; and look for profit plays in ancillary sectors, Fitz-Gerald says.