At every wedding I have attended, I have seen that the Chattan (groom) arrives at the chuppah before the kallah (bride).
Is this a halachic requirement? Please provide both a source as well as the reason for this.
The Rama (Even HaEzer 55:1) quotes the Ran that the Chuppa is the bride going into the domain of the husband.
So it makes sense for the husband to be there first, so the Chuppah could rightfully be called "his house"
The Likkutei Maharich also quotes the Zohar which mentions Gershon's answer (that it's derived from the verse "I gave my daughter to this man").
A reason I have heard is that similar to the Chupa of Adam and Chava like is explained in more detail by Rabbi Bernie Fox with the Orthodox Union.
In context, the Torah says that Chava was brought to Adam.
And the Lord God built the side that He had taken from man into a woman, and He brought her to man.