Final answer:
April goes to Mark's place because he invites her on Wednesday for a walk on a nice day.
Step-by-step explanation:
April goes to Mark's place because she is invited by Mark to visit him on Wednesday since it is a nice day and they can go for a walk.
This is mentioned in the passage: 'This is the first day it hasn't rained in weeks,' she explained, “an' I thought it would be nice to walk.' Mark also offers to take April to Mark's place on Washington's Birthday, which falls on the next Wednesday.
This information can be found in the passage: 'I tell you what, we'll go over there Washington's Birthday. That's this next Wednesday; sure, they'll be glad to see you.'
So, the In April Raintree, April go to Mark's place to meet him.