This post from 2011 considers the question how much time one should take when connecting from an international flight to domestic transportation in the United States. Most answers report one should take 3 hours. The Swedish news reported that due to the 2013 sequestration, the time it takes for Swedish citizens to go through customs and immigration will increase by four hours. I suppose it's the same for Swedish as for others that can visit on a Visa Waiver.
Adding those facts implies one should take seven hours for connecting public transportation, which effectively means one shouldn't try connecting transportation the same day as arriving. Is this accurate? Considering the 2013 sequestration, how much time should one take for a connecting flight to the USA?