The first decade of the 21st century, like the first decade of the 20th, is an age of empire. A hundred years ago, however, there were many empires. They included both the overseas empires of the national states of western Europe--particularly those of Britain, France, Portugal and the Netherlands--and the overland empires of the multinational states ruled by the Habsburg, Romanov and Ottoman dynasties. Today, there is only one empire--the global empire of the United States, a state which is neither national nor multinational in the traditional sense, but which is more accurately described as multicultural and transnational. This new and historically strange American empire is the context and the arena in which all the great and global events of our time are taking place.
The first decade of the 21st century, like the first decade of the 20th, is also an age of immigration. A hundred years ago, large numbers of people were leaving the national states and imperial metropoles of western Europe to emigrate to their colonies or to the United States. At the same time, many people were leaving the rural hinterlands of the multinational states of central and eastern Europe to migrate to their metropolitan centers, or, again, to the United States. Today, however, the direction of imperial migration is largely the reverse of the western pattern, while reminiscent of the former central and eastern one. Large numbers of people have left the former colonies of the west European empires to emigrate to their once-imperial metropoles. At the same time, many people have left the current dominions of the American empire to emigrate to the United States. A century ago, the United States was receiving many immigrants from Europe, but not from its recently-acquired empire in the Caribbean and the Philippines. Today, the United States is receiving many immigrants from its long-established empire in Latin America and East Asia, but not from Europe.