Text Messaging App adding a "1" before a Number

My text messaging app for Android on my Moto G5 Plus phone is adding a "1" before a long distance number and then rejecting the message.  I went into my contact, took the "1" out of the cellphone # and tried to send a new message.  The messaging app added a "1" again.  I went into the app settings, but could find nowhere to change it.  I then went into my phone settings/apps/Messaging and cleared the cache and the data and stopped the app.  I then tried to send another message and it added the "1" before the cell #.  What am I not doing?!

Previous solution from 2015 does not help.

Thanks!

Janet