The most likely reason would be that this city has either been expanding and with that effectively decreasing the amount of available living spcace the animals and trees as well have, at the same time it is possible that this city has been emiting increased amounts of the different types of pollution - one example being light polution which can strongly influence certain ecological niches.
To complete what they needed done
3/4s of the States are needed to ratify an amendment to the Constitution.
Today, this would mean that 38 states would need to approve an amendment at the state level for the amendment to be added.