This is a fantastic question, and I would like to give one piece of meta-advice which I hope will be welcome: the very question of how we got to now is going to depend on what historian you're asking and what their biases and prior assumptions are. Ask a leftist like Howard Zinn how we got to now and he'll tell you a very different story than a conservative historian like Victor Davis Hanson. These guys have different views about what we are, and the story each of them is going to tell about how we got here is going to be very different. I think it was Voltaire who said something to the effect of "history is philosophy taught by example." History has a way of making the historian look like he's telling you the absolute and objective truth when he's really giving you his own worldview without realizing that the truth and his worldview are not one and the same.

That said, if you want to understand the most important event in American history (the Civil War), I cannot say enough good things about Battle Cry of Freedom by James McPhearson.

In terms of understanding American foreign policy, I highly recommend listening to the lecture Imperial by Design by John Mearsheimer. He gives a compelling account of the grand sweep of American foreign policy from a Realist perspective, and I find that the way he presents the topic helps you understand how to think like a Realist.

It seems your interests are pretty closely related with mine! Apologies if I go a little overboard with the suggestions.

As your transferring to the journalism field, I'd highly recommend the essays of two historians/journalists/public intellectuals: Timothy Garton Ash and Tony Judt. Both are concerned with analyzing what Ash calls "the history of the present." While both are Europeanists, a great deal of their writings for the general public concern the United States. In particular, I'd recommend several of Judt's and Garton Ash's essay collections:

Tony Judt, When the Facts Change: Essays, 1995-2010

Tony Judt, Reappraisals: Reflections on the Forgotten Twentieth Century

Timothy Garton Ash, Facts are Subversive: Political Writing from a Decade Without a Name

For more traditional historical works, I think the following are absolutely essential to understanding contemporary American politics and society:

James T. Patterson, Restless Giant: The United States from Watergate to Bush V. Gore. I would start with this one. It's both the broadest overview of recent American history while also being well-written.

Daniel Rodgers, Age of Fracture. Focuses on American intellectual life from the 1970s to the War on Terror. The writing is pretty theoretical and dense, but it's an incredibly rewarding book.

Godfrey Hodgson, More Equal Than Others: American from Nixon to the New Century.

Sean Wilentz, The Age of Reagan: A History, 1974-2008. This is a very good political history, and Wilentz does a particularly good job on the presidential elections of the period.

Dan T. Carter, The Politics of Rage: George Wallace, the Origins of the New Conservatism, and the Transformation of American Politics

For U.S. foreign relations, I suggest:

Hal Brands, Making the Unipolar Moment: US Foreign Policy and the Rise of the Post-Cold War Order

Daniel Sargent, A Superpower Transformed: The Remaking of American Foreign Relations in the 1970s.

David Farber, Taken Hostage: The Iran Hostage Crisis and America's First Encounter with Radical Islam

Justin Vaisse, Neoconservatism: The Biography of a Movement

Derek Chollett and James Goldgeier, America Between the Wars: From 11/9 to 9/11

Andrew Bacevich, America's War for the Greater Middle East

For works that have placed 9/11 and the War on Terror in historical perspective, I suggest:

Joseph Marguiles, What Changed When Everything Changed: 9/11 and the Making of National Identity

Mary Dudziak, editor, September 11 in History: A Watershed Moment?