Answer:
If I had the power to add one amendment to the US constitution, it would be to give basic labor rights.
Step-by-step explanation:
While the constitution talks out basic human rights, freedom of speech and even the right to bear arms, it does not provide any framework on how to manage an effective and healthy workforce fairly.
Some key points would be added e.g the right to a fair minimum wage, the right to health insurance, a work week of no more than 40 hours etc.
While it may have not been important in a society that was largely agricultural, in today's post-industrialization world, this is very important.