I decided to play around with the numbers. As a former high school Mathlete who has since studied mainly humanities, I still have a soft spot for number crunching.
I only looked at the data for the Senate because it's easier. (100 < 435)
First, let's look at the scoring rank. The range goes from -1.00 (most liberal) to 1.000 (most conservative). The DW-Nominate system takes into account every vote taken and analyzes how members of Congress vote in relation to their peers past and present.
Below, I've ordered them left to right and broken them into groups. I think the ranking looks about as I would expect it (save for swapping Durbin and Merkley). I dropped Cowan and Chiesa in favor of keeping Markey and Booker, although their scores are dependent on only a subsection of votes.
Jay Rockefeller (D-WV) at -0.389 marks both mean and median of the Democratic caucus. Deb Fischer (R-NE) marks the Republican median. The mean is 0.555, right between the two senators from Kansas (Moran and Roberts).
The Democratic Caucus:
More than 0.600 from the center: 1
-0.693 Sanders (I-VT)
0.500-0.599 from the center: 9
-0.590 Murphy (D-CT)
-0.578 Hirono (D-HI)
-0.575 Markey (D-MA)
-0.539 Warren (D-MA)
-0.524 Whitehouse (D-RI)
-0.522 Baldwin (D-WI)
-0.511 Durbin (D-IL)
-0.508 Brown (D-OH)
-0.504 Schatz (D-HI)
0.400-0.499 from the center: 16
-0.497 Harkin (D-IA)
-0.488 Boxer (D-CA)
-0.487 Franken (D-MN)
-0.484 Reed (D-RI)
-0.477 Gillibrand (D-NY)
-0.455 Cardin (D-MD)
-0.455 Menendez (D-NJ)
-0.453 Blumenthal (D-CT)
-0.451 Booker (D-NJ)
-0.448 Leahy (D-VT)
-0.440 Levin (D-MI)
-0.432 Merkley (D-OR)
-0.424 Reid (D-NV)
-0.423 Schumer (D-NY)
-0.422 Udall (D-NM)
-0.414 Mikulski (D-MD)
0.300-0.399 from the center: 13
-0.394 Stabenow (D-MI)
-0.389
Rockefeller (D-WV)
-0.381 Wyden(D-OR)
-0.378 Murray (D-WA)
-0.359 Coons (D-DE)
-0.357 Casey (D-PA)
-0.356 Heinrich (D-NM)
-0.352 Cantwell (D-WA)
-0.350 Feinstein (D-CA)
-0.338 Shaheen (D-NH)
-0.329 Johnson (D-SD)
-0.323 Kaine (D-VA)
-0.302 Heitkamp (D-ND)
0.200-0.299 from the center: 13
-0.284 Carper (D-DE)
-0.283 Klobuchar (D-MN)
-0.282 Begich (D-AK)
-0.279 Udall (D-CO)
-0.277 Tester (D-MT)
-0.267 Bennet (D-CO)
-0.266 Warner (D-VA)
-0.264 King (I-ME)
-0.262 Nelson (D-FL)
-0.257 Landrieu (D-LA)
-0.256 McCaskill (D-MO)
-0.236 Hagan (D-NC)
-0.203 Donnelly (D-IN)
Less than 0.200 from the center: 3
-0.193 Baucus (D-MT)
-0.189 Pryor (D-AR)
-0.109 Manchin (D-WV)
----
The Republican Caucus
Less than 0.200 from the center: 2
0.038 Collins (R-ME)
0.128 Murkowski (R-AK)
0.200-0.299 from the center: 1
0.288 Kirk (R-IL)
0.300-0.399 from the center: 3
0.354 Alexander (R-TN)
0.372 Cochran (R-MS)
0.388 Hatch (R-UT)
0.400-0.499 from the center: 14
0.403 Hoeven (R-ND)
0.404 Graham (R-SC)
0.404 McCain (R-AZ)
0.415 Corker (R-TN)
0.429 Flake (R-AZ)
0.436 Ayotte (R-NH)
0.443 Portman (R-OH)
0.459 Heller (R-NV)
0.468 Blunt (R-MO)
0.472 Isakson (R-GA)
0.476 Wicker (R-MS)
0.478 Johanns (R-NE)
0.495 Coats (R-IN)
0.495 Grassley (R-IA)
0.500-0.599 from the center: 8
0.528 Chambliss (R-GA)
0.538 Boozman (R-AR)
0.549
Fischer (R-NE)
0.551 Moran (R-KS)
0.560 Roberts (R-KS)
0.564 Burr (R-NC)
0.568 Thune (R-SD)
0.572 McConnell (R-KY)
More than 0.600 from the center: 17
0.620 Rubio (R-FL)
0.624 Shelby (R-AL)
0.637 Toomey (R-PA)
0.653 Cornyn (R-TX)
0.654 Barasso (R-WY)
0.689 Coburn (R-OK)
0.689 Enzi (R-WY)
0.694 Sessions (R-AL)
0.723 Risch (R-ID)
0.726 Crapo (R-ID)
0.727 Johnson (R-WI)
0.749 Vitter (R-LA)
0.763 Inhofe (R-OK)
0.780 Scott (R-SC)
0.961 Cruz (R-TX)
0.994 Paul (R-KY)
0.995 Lee (R-UT)
Whereas only 10 members of the Democratic caucus are more than 0.500 from the center mark, 25 Republicans (over half of the caucus) are. Only 1 member of the Democratic caucus (Sanders--who isn't even a Democrat) is more than 0.600 from the center mark; 17 Republicans (over one-third of the caucus) are.
There are 16 members of the Democratic caucus within 0.300 from the center mark--as opposed to 3 members of the Republican caucus.
Now, let's look at the difference between the DW-N scores of the members of each state:
In 23 states, that difference is less than 0.100. 14 of these states have two Democratic senators. 9 have two Republican senators.
0.003 Idaho
0.004 New Jersey
0.009 Kansas
0.012 Colorado
0.025 Arizona
0.026 Washington
0.035 Wyoming
0.036 Massachusetts
0.040: Rhode Island
0.041 Maryland
0.046 Michigan
0.051 Oregon
0.054 New York
0.056 Georgia
0.057 Virginia
0.061 Tennessee
0.066 New Mexico
0.070 Alabama
0.071 Nebraska
0.072 Hawaii
0.074 Oklahoma
0.075 Delaware
0.084 Montana
In 5 states, the difference between the DW-N scores of the two senators is between 0.100 and 0.250:
0.104 Mississippi
0.137 Connecticut
0.138 California
0.204 Minnesota
0.245 Vermont
In 6 states, the difference between the DW-N scores of the two senators is between 0.250 and 0.500.
0.280 West Virginia
0.302 Maine
0.308 Texas
0.376 South Carolina
0.410 Alaska
0.422 Kentucky
In WV, TX, SC, and KY, one senator is much more conservative than the other even though both are of the same party. Maine and Alaska are split.
In 16 states, the difference between the DW-N scores of the two senators is above 0.500.
0.607 Utah
0.698 Indiana
0.705 North Dakota
0.724 Missouri
0.727 Arkansas
0.774 New Hampshire
0.799 Illinois
0.882 Florida
0.883 Nevada
0.897 South Dakota
0.900 North Carolina
0.951 Ohio
0.992 Iowa
0.994 Pennsylvania
1.006 Louisiana
1.249 Wisconsin
Excluding Utah, all of these states have one Democratic senator and one Republican senator. The starkest divide is in Wisconsin, which has one very liberal senator (Baldwin) an one very conservative senator (Johnson).
Now, let's look at the mean score for each state.
-0.571 Vermont
-0.557 Massachusetts
-0.547 Hawaii
-0.522 Connecticut
-0.504 Rhode Island
-0.453 New Jersey
-0.450 New York
-0.435 Maryland
-0.419 California
-0.407 Oregon
-0.389 New Mexico
-0.385 Minnesota
-0.365 Washington
-0.322 Delaware
-0.295 Virginia
-0.273 Colorado
-0.249 West Virginia
-0.225 Montana
-0.113 Maine
-0.112 Illinois
-0.077 Alaska
-0.033 Ohio
-0.001 Iowa
0.018 Nevada
0.049 New Hampshire
0.056 North Dakota
0.103 Wisconsin
0.106 Missouri
0.120 South Dakota
0.140 Pennsylvania
0.146 Indiana
0.246 Louisiana
0.385 Tennessee
0.417 Arizona
0.424 Mississippi
0.500 Georgia
0.514 Nebraska
0.556 Kansas
0.592 South Carolina
0.659 Alabama
0.672 Wyoming
0.692 Utah
0.707 Texas
0.725 Idaho
0.726 Oklahoma
0.793 Kentucky
In 5 states, the mean score of the two senators is more than 0.500 left of center: Vermont, Massachusetts, Hawaii, Connecticut, and Rhode Island.
In 11 states, the mean score of the two senators is more than 0.500 right of center: Georgia, Nebraska, Kansas, South Carolina, Alabama, Wyoming, Utah, Texas, Idaho, Oklahoma,and Kentucky.
