The counties of Essex and Hudson, New Jersey, measured by population, are two of the largest political units of their kind in the country.

These counties are not only almost exclusively of an urban character; they have become practically continuous urban communities.

The physical unity of Essex County, however, is more real than the social. Underneath the common interests of each of the several localities is a strong local spirit, due largely to individuality of interest. Some of them are almost exclusively residential and suburban, tributary not to the large city of Newark, but to New York. The cities of Newark and Jersey City have all the varied characteristics of a metropolis. They have an independent reason for existence in their manufacturing interests, and what usually goes with such interests, a large foreign population.