What does CD stand for here?

[NewHopeR]

Context:

Even in a political climate hostile to Republicans across the nation in 2006, Smith won re-election with 66% of the vote, the highest percentage for any Republican in the New Jersey delegation.^[8]
Smith faced a challenge from Democrat Joshua M. Zeitz in 2008, who raised far more money than any of Smith's previous opponents. Despite the very difficult political climate for Republicans, Smith won re-election 66%-32%. McCain won the district by a narrower margin as the 4th CD was one of only three he won in the state.^[9]

[SoothingDave]

Congressional District.