This is a link I found showing a conversation between Chipp Kidd and Milton Glaser. The conversation is long, which is why I chose to post a link. The conversation starts by Chipp Kidd asking Milton Glaser about his I “heart” New York campaign. Glaser states that the logo arose during a time of low moral for New York. It also became a campaign for tourism. Later after 9/11 Glaser discusses for the notion for I love New York changed.
They also discuss Glaser’s early influences on his designs.