In the AHTUS, why does the xtimewt weight have values of -999998 for cases in which recwght is not missing?

These cases come from various states–including NY. So why do they receive a value of -999998 for the xtimewt? For these cases, should I use the recwght value instead?

These negative values are errors. They should be “0s” for the purposes of comparability. For more on this see the variable description for XTIMEWT. This error has been fixed and should be reflected after the next data release.