Texas and New Mexico on Tuesday reported an increase of 28 cases of measles in the last five days, bringing the total known infections to 256 in the two states since an outbreak began in late January.

Six years ago, two communities in New York – one in Brooklyn and one in Rockland County – were facing the worst measles outbreaks the United States had seen in decades. It was the closest the nation has gotten to losing elimination status for the extremely contagious disease,