Definition of carriage trade in English:

carriage trade

noun

North American
informal
  • [mass noun] The wealthy clientele of a business:

    ‘determined to pursue the carriage trade, she quickly established an old-girl network’
    • ‘Later, in 1883, it became a citrus farm, and finally in 1893 a holiday destination for the wealthy passengers of the East Coast carriage trade.’

Origin

With reference to people who formerly would have been wealthy enough to maintain a private carriage.