"This Land is Your Land" vs. "God Bless America"

I had a hard time finding music that specifically related to my thesis ideas, so instead I tried to find songs that had to do with American Studies more generally.
In high school, we briefly discussed the origins of the song "This Land is Your Land," by Woody Guthrie (who was, incidentally, one of the Bruce Springsteen's main inspirations. Springsteen does a great cover of "This Land is Your Land" here.) I found this really interesting article on NPR that goes into much more detail than I had ever encountered. Guthrie was frustrated by Irving Berlin's "God Bless America," which was at the time (the 1930s) enormously popular. In response, he wrote what would become "This Land is Your Land," but originally sarcastically called it "God Blessed America for Me." The NPR article includes many interesting lyric revisions and omissions that show the song's evolution before being recorded and released. (Final lyrics are here.) Earlier versions contained much more overtly critical lyrics with Communist undertones. Guthrie's daughter attributed the modifications to the anti-Communist hysteria that increased dramatically around the time it was recorded, or just before the McCarthy years.
Using this music as a historical source is fascinating, especially since both songs are so prominent in modern culture. I grew up singing this song in school and at summer camp with no conception of its history or deeper meaning, and I wonder how the song culturally shifted so drastically from a place of anger and criticism to becoming a standard patriotic children's song.