Among philosophers, his 1970's Theory of Justice is considered the greatest work of political philosophy and ethics of the 20th century, and the first real attempt at a foundational political ethics system since the 19th century with utilitarianism and Marxism. I linked to the shorter, updated book intended for a mainstream audience, as the original is a bit heavy going.

Nozick's book can be said to be the definitive rejoinder to Rawls, and the ethical foundation of much of American libertarianism today.

Most US political ethics debates still to this day boil down to Rawls vs. Nozick in my view, though many still harken back to 19th century ideas of utilitarianism and liberty as they go more "extreme" (eg. hard Marxists, or hard anarcho-capitalists). Rawls and Nozick at least attempt to deal with history and disadvantaged peoples.

As usual, its hard to separate politics, justice, and economics, though we often try: the end result is intertwingled.