The pipeline would transport oil from fields in Canada down to the Gulf States, but Consumer Watchdog says the impact is much greater. "Gas prices in America, gas prices in the Midwest, gas prices in California, are going to go up," says Consumer Watchdog Executive Director Jamie Court.

Court estimates the price of gas in California could go up 8 cents a gallon. In the Midwest, prices would rise 25 to 40 cents a gallon. That's because the Midwest gets most of its oil from Canada. Consumer Watchdog says the real purpose of the pipeline would be to transport oil to world markets.

The study by Consumer Watchdog found that increasing the demand for this oil would increase the prices for oil by $30 a barrel. "Consumer spending is what would be affected and consumer spending goes more directly into reviving the economy than any other kind of spending," explains Judy Dugan with Consumer Watchdog.

The cost to the U.S. economy is estimated to be $3 billion to $4 billion. "That's going to ripple through both interms of people driving to work, running around and doing their errands, getting to vacation, but it's also going to be in terms of delivering things to market," says businessman Tom Steyer.

TransCanada Corporation says the oil that would be delivered through the pipeline is much needed in the United States. The company says increasing the supply would mean lower prices for crude oil, resulting in lower gas prices.