Below is our spreadsheet containing presidential election results for the 2008 election between Democrat Barack Obama and Republican John McCain according to the new congressional district lines created during the 2011-12 redistricting process. For presidential election results for the 2000 & 2004 elections (under old district lines), click here.
For the sake of comparison, we have also included results for the same election under the old lines that were used in the 2008 election. This data was also compiled by us, and you can review our earlier work here. Note that some states, such as California, have renumbered their districts, so direct comparisons between districts sharing the same number are not always possible. New districts and discontinued districts are noted with dashed lines in the appropriate columns.
In the right-most column, we include our best assessment for each new district's corresponding "old district number". Be careful, though, because it's not an exact science—some districts have clear predecessors, while others don't. Here's our general methodology:
• If an incumbent is retiring but it's reasonably clear where they would have sough re-election, then his or her old district number is used. For example, Gary Ackerman was planning to run in NY-06 before announcing his retirement, so his old district, NY-05, is marked as the predecessor.
• If two incumbents are facing off against each other, we've marked both districts as predecessors. For example, see CA-30. If one incumbent has already won a primary, then we leave only the winner's district. For example, see PA-12. (Sorry, losers.)
• If a district is newly created thanks to reapportionment, then we have not marked any predecessor. Example: AZ-09. Note that in some cases, states have renumbered, or incumbents have made particular re-election choices, so that the "new" districts are not always those with the highest number. Example: UT-02, as mentioned above.
Beyond this, we've had to make some judgment calls, mostly in California, where the lines were completely overhauled. Note: The old Obama/McCain numbers reflect those for the same district number. So the new results for AZ-02 (for example) reflect the district that Dem Rep. Ron Barber will seek re-election in this fall. But the old results for AZ-02 refer to GOP Rep. Trent Franks' current district. It is necessary to manually match up old results to new district numbers for a more direct comparison. So if you want to see what AZ-02's "old" results look like, first find its predecessor district (in this case, AZ-08), then look at the old Obama/McCain numbers for that seat number.