Raw Data In The 2016 U.S. Presidential General Election Race

tl;dr Clinton is far ahead of Trump in the general election race at this point.

Summary

Presidential elections are decided on a state by state basis, so the best tools to predict their outcome are conventional wisdom based upon past voting behavior in a state, and state by state general election polling. The conventional wisdom (per CNN) and Clinton v. Trump State Level General Election Polls (per Real Clear Politics and Wikipedia) are presented below.

The threshold to win is 270 electoral votes out of 538 available electoral votes, all of which are in principle bound by the November 8, 2016 election results (although many states allow early voting, and Washington at least used to allow votes to be mailed on election day itself).  All states except Maine and Nebraska award all of their electoral votes to the plurality winner in the state.  Maine and Nebraska allocate some electoral votes based on Congressional District, but in practice this usually mean one extra GOP electoral vote in Maine and one extra Democratic electoral vote in Nebraska, resulting in the same result as if all states were winner take all.

All lean Republican and lean Democratic states and all but two battleground states have polling. Solid Republican and Solid Democratic states are assumed to vote as conventional wisdom expects unless a poll contradicts that expectation.  Clinton is expected to win the two battleground states that do not have polling (CO and NV) based upon strong Obama wins in those states in 2008 and 2012, although both of these states did back George W. Bush in 2000 and 2004.

Clinton: 374 electoral votes
Tied: 6 electoral votes (Utah)
Trump: 168 electoral votes.

The only states defying CNN's conventional wisdom in polling are Arizona and Georgia which lean Republican but support Clinton, and Utah which is safe Republican but tied.

Polling in seven battle ground states support Clinton (FL, IA, NH, NC, OH, WI, VA).  Clinton has the advantage based upon past Presidential election results in the two battleground states where polling is not available (CO, NV).

The states with polling that have less than a 4 point margin for one candidate or another are: Ohio (Clinton + 3.5), Arizona (Clinton +3.5) Utah (tie), Missouri (Trump +1.5), and Mississippi (Trump +3). The margins of error in the polls are large enough that Trump could lose one of those states simply because polling was inaccurate due to random sampling error.

A slide in Trump support could turn a Clinton lead into an even greater landslide. Clinton support would have to drop 7 percentage points on average for Trump to win (possibly more depending on the polling in CO and NV).  The marginal states at this point are Florida and Arizona.

In national polling, which is less relevant, Clinton leads Trump, on average 47.3 to 40.9, based on an average of seven recent national polls from April 11 to May 9.  The number of percentage points Clinton needs to slide for Trump to lead in national polls (6.4) is almost the same as the number of percentage points Clinton needs to slide for Trump to lead in state polls sufficient to win 270 electoral votes (7), especially considering that the later number includes some rounding error.

We also have no polling from Arkansas, which would ordinarily be a safe Republican state, but may not be with Hillary Clinton, its former first lady, running for President.  Clinton leads in three battleground Southern states (VA, NC and FL) already and Trump's support is soft in two more ordinarily safe Republican states (GA and MS), and Trump trails Clinton badly in Arizona which while not in the South has a lot of Southern transplants. Clinton dominated primary voting in the South despite strong Sanders support elsewhere, demonstrating her enthusiastic support from the base there and familiarity with how to deliver a political message that resonates in the South.  So, Arkansas's six electoral votes could be in play this year as well.  A win in Arkansas would tip the Clinton-Trump electoral college balance even further in her favor.

Some other safe Republican states were very emphatic in their rejection of Trump during the primary season: Idaho, Utah, Wyoming, and Kansas all wanted nothing to do with him. This doesn't mean that Clinton will be viewed as the lesser of two evils in these solidly red states, but his supporters certainly won't be very enthusiastic in those states and he is tied in Utah polling.  Kansas voters still prefer Trump, but we have no general election polling out of Idaho or Wyoming.

The race is almost sure to tighten between now and election day in six months.  But, it isn't obvious that it will tighten enough to allow Trump to prevail in the general election. CNN's prediction market currently gives Clinton a 71% chance of winning and Trump a 29% chance of winning, which in my opinion isn't far from the mark.

State by state polling data, and CNN's conventional wisdom, appears below the break. Where multiple polls are present for a state, the results for the state are the average (without weighting) of the polls that are not stale.  Stale polls, shown in italics, are ignored.

Solid Republican (164 total): Alabama (9), Alaska (3), Arkansas (6), Idaho (4), Indiana (11), Kansas (6), Kentucky (8), Louisiana (8), Mississippi (6), Missouri (10), Montana (3), Nebraska (5), North Dakota (3), Oklahoma (7), South Carolina (9), South Dakota (3), Tennessee (11), Texas (38), Utah (6), West Virginia (5), Wyoming (3)

AK Trump +5.2
January 2016 (Alaska Dispatch/Ivan Moore Research): Alaska 44.1-49.3
Alaska gave only 38% of its vote to Obama in 2008 twenty-one percentage points behind his GOP opponent, and 41% in 2012 fourteen percentage points behind his GOP opponent.

IN Trump +7.5
May 1( NBC/WSJ/Marist): Indiana 41-48
April 22 (WTHR/Howey Politics): Indiana 39-47

KS Trump +10 
February 26 (Ft. Hayes Univ.) Kansas 36-46

LA Trump + 16
May 6 (JMC Analytics and Polling) Louisiana 36-52

MO Trump + 1.5
March 24 (DFM Research) Missouri 42-40
March 10 (Ft. Hayes Univ.) Missouri 38-43

MS Trump +3
March 31 (Mason-Dixon): Mississippi 43-46

UT Tie
April 5 (Dan Jones & Associates): Utah 38-38
March 15 (Dan Jones & Associates): Utah 38-36

WV Trump +27
May 3 (PPP (D)): West Virginia 30-57

Leans Republican (27 total): Arizona (11), Georgia (16)

AZ Clinton +3.5
April 25 (Behavior Research Center): Arizona 42-35
March 11 (Merrill Poll/West Group): Arizona 38-38

GA Clinton +6
May 7 (WSB-TV/Landark): Georgia 41-42
April 3 (Lake Research): Georgia  50-37

Battleground states (110 total): Colorado (9), Florida (29), Iowa (6), New Hampshire (4), Nevada (6), Ohio (18), Virginia (13), Wisconsin (10), North Carolina (15)

CO Advantage Clinton
We have no Clinton v. Trump polls in Colorado yet.  But, Colorado voters supported President Obama by 54% with 2008 leading his GOP opponent by 9 percentage points, and with 51%, leading his GOP opponent by 5 percentage points, in 2012.  Also notably, all of Colorado primary delegates were awarded to Cruz - Trump did not receive a single national convention delegate in Colorado.

FL Clinton +7
May 10 (Quinnipiac): Florida  43-42
May 1 (AIF (R)): Florida 49-36

IA Clinton +4 
January 10 (PPP (D)): 42-42
January 7 (NBC/WSJ/Marist): 48-40
Iowa backed Obama with 54% in 2008 leading his GOP opponent by 10 percentage points, and with 52% in 2012 leading his GOP opponent by 6 percentage points.

NC Clinton +4.5
May 5 (Cititas (R)): North Carolina 49-40
April 27 (PPP (D)): North Carolina 44-44

NH Clinton +12
May 9 (Dartmouth): New Hampshire 34-29
April 21 (WMUR/UNH): New Hampshire 50-31

NV Advantage Clinton
We have no Clinton v. Trump polls in Nevada yet.  But, Nevada voters supported President Obama by 55% leading his GOP opponent by 12 percentage points, and with 52% in 2012 leading his GOP opponent by 6 percentage points.

OH Clinton +3.5
May 10 (Quinnipiac): Ohio 39-43
May 2 (PPP (D)): Ohio 45-42
March 10 (Marist): Ohio 48-42
March 6 (PPP(D)): Ohio 45-40
March 6 (CNN/ORC): Ohio 50-43

WI Clinton +11.5
April 20 (WPR/St. Norbert): Wisconsin 46-34
April 4 (Emerson): Wisconsin 47-37
March 31 (Fox Business): Wisconsin 49-35
March 30 (Marquette): Wisconsin 47-37

VA Clinton +9
April 6 (Christopher Newport University): Virginia 44-35

Leans Democratic (36 total): Michigan (16), Pennsylvania (20)

MI Clinton +12.3
March 25 (SurveyUSA): Michigan 49-38
March 22 (EPIC-MRA): Michigan 47-37
March 3 (NBC/WSJ/Marist): Michigan 52-36

PA Clinton +4.7
May 10 (Quinnipiac): Pennsylvania 43-42
April 24 (NBC/WSJ/Marist): Pennsylvania 54-39
April 10 (Fox News): Pennsylvania 44-44
April 6 (Quinnipiac): Pennsylvania 45-42

Solid Democratic (201 total): California (55), Connecticut (7), Delaware (3), DC (3), Hawaii (4), Illinois (20), Maine (4), Maryland (10), Massachusetts (11), Minnesota (10), New Mexico (5), New Jersey (14), New York (29), Oregon (7), Rhode Island (4), Vermont (3), and Washington (12).

CA Clinton +27.8
May 2 (KABC/Survey USA): California 56-34

April 7 (Field): California 59-31
April 4 (SurveyUSA): California 60-26
March 28 (LA Times): California 57-30

CT Clinton +8
April 12 (Emerson): Connecticut 48-40

IL Clinton +25
March 10 (Marist): Illinois 57-32

MA Clinton +30
May 9 (Boston Globe/Suffolk): Massachusetts 55-31
April 11 (Western NE University): Massachusetts 62-26

MD Clinton +34.7
April 19 (PPP (D)): Maryland 61-28
April 13 (NBC 4/Marist): Maryland 63-27
April 6 (Wash Post/U. of MD): Maryland 63-28

MN Clinton +13
April 27 (Star Tribune): Minnesota 48-35

NJ Clinton +14

April 20 (Rutgers-Eagleton): New Jersey 50-36

NY Clinton +24.2
May 3 (Siena): New York 56-30
April 18 (Emerson): New York 55-36
April 12 (PPP (D)): New York 55-35
April 11 (NBC/WSJ/Marist): New York 61-32
April 10 (Fox News): New York 53-37
April 8 (Emerson): New York 54-36
March 31 (Quinnipiac): New York 53-33