The 1970s were a period of economic uncertainty. Beginning in 1973, the Organization of Petroleum Exporting Countries (OPEC) issued an embargo on Middle Eastern oil. This impacted the price of a barrel of oil and subsequently lowered OPEC profits. The US also was needed to intervene in the Yom Kippur War of 1973. The price for a barrel of oil skyrocketed in 1974. Americans were forced to ration gasoline by only purchasing the product on specific days. Unfortunately, while the embargo ended in 1974, inflation and unemployment steadily rose through the rest of the decade. At the end of the decade, 1979 marked the beginning of the Iranian Revolution and, ultimately, the rise in oil cost. Oil prices rose again during the late 1970s and Americans were forced once again to ration gasoline. President Carter attempted to curb the energy and economic crisis, When President Reagan took office in 1981, times began to change, but new challenges lay ahead for the US and the world.