Could the Massachusetts State Senate or Wyoming State Senate become all D/all R soon?

[Zaybay]

Wyoming is unlikely because I think the two seats represented by Ds are significant Native areas. 

There’s also the point that both Wyoming, a very urban mountain state, and Massachusetts, a pretty catholic white ethnic state, are trending towards being more competitive, not less. 

Wyoming:

2000- 68/28 (R+40)
2004- 69/29 (R+40)
2008- 65/33 (R+32)
2012- 69/28 (R+41)
2016- 67/22 (R+45)
2020- 70/27 (R+43)

Really strong D trend there.

Massachusetts:

2000- 60/33 (D+27)
2004- 62/37 (D+25)
2008- 62/36 (D+26)
2012- 61/38 (D+23)
2016- 61/33 (D+28)
2020- 66/32 (D+34)

Man, that R trend is crazy.

[Zaybay]

Now, I cannot speak about the WY State Senate, and based on the discussion so far it sounds like its impossible due to the safe Teton county seat.

What I can speak for is the MA State Senate. Now, on paper, the MA state senate could become all D, but in practice, I have my doubts.

Lets start with the districts that make up the state. Using the 2016 election as a baseline, Trump was only able to win 3 districts in the state. These seats are (and fair warning, Massachusetts uses names based on counties):

Worcester, Hampden, Hampshire and Middlesex: 51/40 Trump +11
Worcester and Norfolk: 47/45 Trump +2
1st Plymouth and Bristol:48/46 Trump +2

Clinton was able to win all the other 37 seats.

Now, whats interesting is that, of the three Trump-won seats, Republicans actually only hold one of them, Worcester and Norfolk held by Ryan Fattman. The Trump +11 seat is held by a Democrat, as is the 1st Plymouth and Bristol.

So what seats make up the Republican delegation? Besides Worcester and Norfolk, the GOP hold two additional seats, those being:

1st Essex and Middlesex: 39/53 Clinton +14
Plymouth and Norfolk: 39/53 Clinton +14

So overall, the GOP delegation is concentrated in a seat that barely went to Trump in 2016, and two double-digit Clinton seats. On paper, its completely possible that the entire state senate could be flipped D, especially since Biden likely won all but the Trump +10 seat, and even then it was likely a seat that Trump barely won.

In practice however, this is easier said than done. These Republican incumbents, along with the Democratic incumbents in the Trump seats, are very entrenched and hold a great degree of popularity.

Lets look at the 2020 state senate elections to illustrate this, since the Democrats made a semi-serious attempt to take down the 4 Republican state senators that the state had at the time:

Dem Held
Worcester, Hampden, Hampshire and Middlesex (Trump +11 in 2016): Dem Senator +6

GOP Held
Worcester & Norfolk (Trump +2 in 2016): GOP Senator +20
Plymouth & Norfolk (Clinton +14 in 2016): GOP Senator +10
1st Essex and Middlesex(Clinton +14 in 2016): GOP Senator Unopposed in the general

The only Republican the Dems took down was Dean Tran of Worcester and Middlesex (Clinton +9), and the only reason he even became a rep was because he won a special election. 2020 was his first general election, and even then he only lost by 1%.

So, to summarize, on paper the task is very possible. In practice, however, its a very difficult battle.