On the topic of if the District of Columbia should qualify as the 51st US State.
And in the second half of the 19th century, Republicans attempted to “stack” the Senate by admitting a large number of Republican states into the union, starting with Nevada in 1864 (population of just 6,857(!) in the 1860 census), Nebraska (1867), Colorado (1876), Montana, Washington, and North and South Dakota as separate states in an 1889 omnibus, and Idaho and Wyoming in 1890.
DC’s current population? ~705,000 people. Slightly more than 6,857.