A large volume of research has acknowledged the role of oil price shocks to generate a significant stagflationary impact on U.S. and other oil importing nations. Recent research however shows a paradigm shift in this oil price-macroeconomy relationship since the mid 1980s, during which the U.S. economy has been relatively resilient to oil shocks. Both output contraction and inflationary expectations have been milder in the post mid 1980s than before. But the 2007-08 oil shock episode has re-emphasized the immense impact of the ebbs and flows of oil prices on the U.S. economys ups and downs. Global oil price peaked at $148 a barrel in June 2008. With the mortgage crisis and credit crunch, oil was another blow too many. The U.S. economy swamped into one of the greatest recessions of all times. According to Hamilton (2009), the 2007-08 oil shock had a significant contribution to the recent recession. While a lot of work have been done on the effects of oil price shocks on the U.S. economy, relatively little work has investigated what triggers oil price increase. My research illustrates why it is important to study the cause of an oil price rise. First, the effects of oil price rise on the macro variables depend heavily on what causes the shock. Secondly, whereas the oil price hikes of the 1970s and early 1980s can mostly be attributed to exogenous events in OPEC (Arab Oil Embargo, Iran-Iraq War, Iranian Revolution), a significant source of oil price spikes in the post mid 1980 era have been an increase in global oil demand confronting stagnating oil production. From a policy perspective, of course, policies aimed at dealing with higher oil prices must take careful account of what causes oil prices to rise. Empirical research that demonstrates the resilience of U.S. economy to oil price shocks builds on the implicit assumption that as oil price varies, everything else in the global economy is held constant. Thus all variations in oil prices are taken as alike and exogenous. This overlooks the possibility that oil price rise sparked off by diverse events can potentially lead to different repercussions. This thesis is an attempt to develop framework to study the endogenous increase in oil price. The oil price increase arises from increase in U.S. growth rate, increase in foreign growth rate and a purely exogenous oil supply shock by OPEC. The most important result is that the source of oil price rise has changed after the mid 1980s - whereas before the mid 1980s, bulk of the variation in oil price was due to supply shocks by OPEC, post mid 1980s, most of the variation in oil price is explained by increase in U.S. and foreign growth. Furthermore, if the origin of the oil price rise is the same, then the responses of most U.S. macroeconomic variables display remarkable similarity in the pre and post mid 1980s. This result gives us a new way to look at the resilience of the U.S. economic activity to oil price rise since the mid 1980s. The resilience can be explained to a significant extent by the fact that the type of shocks resulting in oil price rise has changed.