Some states were actually in color as early as 1947, but most places didn't manage anything other than black, white and muddy brown until as late as 1961.
Yes, but that was completely by choice. They had had the infrastructure to start living in colour for half a decade at that time, however the patriotic conservatives that populated the area preferred to maintain their traditional manner of living.
This all changed in 1962 when it was first proposed that their state of colourlessness be advertised to promote state tourism. This was met with outrage as the people of Mississippi saw their way of life being presented as a disrespected novelty, at which point they conformed with the rest of the United States. This change was met with relatively little death, despite the prevalence of radical colour traditionalists in the State.