UFO "cigar" crosses immense Texas sky

We were on the highway going west. Big empty sky. I was driving our motorhome westbound and the sun was behind us. It could possibly have been a bit before one PM. I noticed a cigar shape in the southern sky going north. It was at 10 O'clock and very distant. It caught my eye as it was extremely far away as big as a city moving in a straight line without any contrail. It would seem it was above our stratisphere. My husband had worked on the space program and was aware of more possibilities than I, as to the distance and size. We were estimating by going against the flat surface of earth, distant mountains and such. I pulled off the highway as quickly as I could and we, including our four children, watched it cross the sky. It was amazing. To get an idea of its size to our eye, it was the length of the breath of my fingernail and as thick as my short nail, a grain of rice!!! In a clear sky moving as fast as it was, was a UFO as nothing made by us could achieve the speed in which this moved at that distance.
Date is approximate.  PD