Complex sentence: In 1947 Iowa purchased an old colonial style home to serve as the residence for the Governor, but by 1970, a new home was needed to serve the needs of the Governor and the state to host visiting dignitaries.
Split into simpler sentences: In 1947 Iowa purchased an old colonial style home to serve as the residence for the Governor. By 1970, it was clear that home couldn't serve the needs of the Governor and the state to host visiting dignitaries.