Why does god save the queen and my country tis of thee sound alike?

"God Save the Queen" and "My Country, 'Tis of Thee" sound alike because they share the same melody. The tune was originally composed in the 18th century and became popular for various lyrics in different contexts. "My Country, 'Tis of Thee," written by Samuel Francis Smith in 1831, was set to this melody, which is why both songs are often associated with patriotic sentiments in English-speaking countries.