The 14 stars in the blue union represent the 14 States, being Arizona, Arkansas, Colorado, Constitution, Lakota, Louisiana, Missouri, Nebraska, Nevada, Salmon, Santa Fe, South California, Texas, and Utah.
The largest star represents the state of Texas, which was a historically consequential state that is now the most powerful and populous part of the nation (though that lore is still a work in progress).
The 13 stripes represent the original 13 colonies of the United States, which in this timeline would've dissolved about a century into the future.
The light blue/cyan line on the fly side represents the Mississippi and Missouri Rivers, which would compose its entire eastern border.