Wagons

4 clues
Carriages
SUV ancestors
Pioneer transports
Horse-drawn vehicles
Similar answers:
Aaronburrconspiracy
Aarons
Aaronsbeard
Aaronsorkin
Aaronspelling
Aaronsrod
Aasponsor
Abandons
Abandonship
Abandonshippie
Abandonshope
Abandonsshop
Abbreviations
Aberrations
Abolitions
Abrasions
Abstentions
Accordions
Accusations
Achesons