Legislation
1935
Social Security Act
-Passed the House 372-33
-Passed the Senate 77-6
-Signed into law by FDR
House
-Dem: Yes — 284 of 319 (89%)
-Rep: Yes — 81 of 102 (79%)
Senate
-Dem: Yes — 60 of 69 (87%)
-Rep: Yes — 16 of 25 (64%)
Source
* * *
1938
Fair Labor Standards Act
-Established minimum wage, 40-hour workweek, and restrictions on child labor
-Passed the House 291-89
-Passed the Senate by voice vote
-Signed into law by FDR
House
-Dem: Yes — 252 of 293 (86%)
-Rep: Yes — 30 of 78 (38%)
Senate
Passed the Senate by voice vote.
Source
* * *
1941
Prohibition of Discrimination in the Defense Industry
-Executive Order 8802
-Banned discriminatory employment practices by Federal agencies and all unions and companies engaged in war-related work
-Established the Fair Employment Practices Commission to enforce the new policy
-Signed by FDR
Source
* * *
1948
Desegregation of Armed Forces
-Executive Order 9981
-Established the President’s Committee on Equality of Treatment and Opportunity in the Armed Services, committing the government to integrating the segregated military
-Signed by Truman
Source
* * *
1963
Clean Air Act
-Passed the House 276 to 112
-Passed the Senate by voice vote
-Signed into law by LBJ
House
-Dem: Yes — 204 of 256 (80%)
-Rep: Yes — 69 of 178 (39%)
Senate
Passed the Senate by voice vote.
Source
* * *
1964
Civil Rights Act
-Passed the House 290-130*
-Passed the Senate 73-27*
-Signed into law by LBJ
House
-Dem: Yes — 152 of 254 (60%)*
-Rep: Yes — 138 of 177 (78%)*
Senate
-Dem: Yes — 46 of 67 (69%)*
-Rep: Yes — 27 of 33 (82%)*
Note: This vote was an important moment in the history of the Republican and Democratic parties and was the major catalyst leading to the transition of Southern Democrats to the Republican Party.*
Senate Votes on the 1964 Civil Rights Act:

* * *
1965
Medicare (Social Security Act Amendments)
-Passed the House 307-116
-Passed the Senate 70-24
-Signed into law by LBJ
House
-Dem: Yes — 237 of 293 (81%)
-Rep: Yes — 70 of 140 (50%)*
Senate
-Dem: Yes — 57 of 67 (85%)
-Rep: Yes — 13 of 32 (41%)*
* * *
1972
Clean Water Act
-Passed the House 366-11
-Passed the Senate 74-0
-Vetoed by Nixon
-Nixon’s veto was overridden by Congress
House Override
-Dem: Yes — 151 of 161 (94%) (92 abstained)
-Rep: Yes — 96 of 109 (88%) (68 abstained)*
Senate Override
-Dem: Yes — 34 of 37 (92%) (17 abstained)
-Rep: Yes — 17 of 25 (68%) (19 abstained)*
* * *
2010
Permitting Gay People to Serve Openly in the Military
-Passed the House 250-175*
-Passed the Senate 65-31*
-Signed into law by Barack Obama
House
-Dem: Yes — 235 of 255 (92%)*
-Rep: Yes — 15 of 179 (8%)*
Senate
-Dem: Yes — 53 of 56 (95%)*
-Rep: Yes — 6 of 32 (14%)*
The Economy
Most economists lean Democratic:

From a 2003 survey of 264 economists
Source

From a 2010 survey of 299 economists
Source
Climate Change
The earth’s climate is extremely important, both economically and biologically. Most Democrats agree with the vast majority of climate scientists that humans have caused all or nearly all of earth’s rapid warming over the past 5-6 decades.* As of 2017, 78% of Democrats agreed that human activity is causing the warming while only 24% of Republicans agree* with the extremely strong scientific consensus.
But, isn’t there still a lot of uncertainty about what’s causing global warming? No. Climate scientists are roughly as certain that humans are causing the rapid warming of the earth’s atmosphere as they are in the basic science of plate tectonics.*
But, is scientific consensus really important? Maybe. One way to look at it is to consider artificial intelligence. Imagine if we looked at research papers of artificial intelligence researchers and polled them and found that 5% of them are warning that there is a high probability of robots taking over the world in the near future. That might be slightly alarming, right? However, if we look at that same information and talk to the same people and find that 97% of those papers and scientists are warning of a robot takeover, governments all over the world would be acting immediately to prevent this.