In 1869 the residents of Hudson County, New Jersey voted on a referendum to consolidate into a Greater Jersey City. Only Union township defeated the referendum, and do to it cutting off the other regions, ending the hopes of uniting the county.
Now what happens if Hudson County is able to consolidate. Its population was about 130,000 which would make it the 11th largest city in the United States. You also have three of the largest cities in the United States (Brooklyn, "Greater" Jersey city, and New York City) in a very small area. Hell, move aside St. Paul and Minneapolis we have the triplet cities.