Wyoming: The first and last rows have one more star than the interior rows. In addition to the 1890 flag, issued after Wyoming became a state, the 26-star, 32-star, and 37-star flags looked like this.
Oregon: The middle row has two fewer stars than all the other rows, as in the 33-star flag issued upon Oregon's statehood. This only works for flags with an odd number of rows.
You can use the widget above to design hypothetical flags of up to 100 stars. The 29-, 69- and 87-star flags are the only ones that cannot be shoehorned into one of these patterns.
Think you've found a pattern for any of these three hypothetical Americas? E-mail me and maybe we'll add your pattern to the widget. In the meantime, it's best to hope the United States doesn't grant statehood to Puerto Rico and all 18 governorates of Iraq.