Related Clues:

• They cross aves.
• Fifth and Mad.
• A and B in D.C., e.g.
• Parts of some grids: Abbr.
• NYC block separators
• Lexington and others, in N.Y.C.
• Urban rtes.
• Brutus' birds
• John, Paul and George: Abbr.
• Paul and John: abbr.
• Class of birds
• Network on a 55-Down: Abbr.
• Lex and Park, e.g., in N.Y.C.
• Elm and Vine, briefly
• Some city map lines: Abbr.