Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Find the Latest Information on the Coronavirus/COVID-19 at FTA's Coronavirus landing page.

United States Department of Transportation United States Department of Transportation

2018 NTD Database Dictionary

A dictionary that defines terms found on NTD Reporting Forms and identifies the 2018 Database File in which they are included. Please note that this does not include terms in the 2018 Data Tables and Time Series files - each of those files includes its own data dicationary.

This document has not been certified as 508 compliant.
NTDHelp@dot.gov