This is not new, it just has its own thread now 
Here is an extensive list of all the routes that fly into/out of IAD in real life, and the gates they park at. With a list this size there is for sure mistakes or missing items, so any help is welcome! Also, despite using 3 sources (flightsfrom.com, flightmapper.net, and FR24), I noticed there are deficiencies. For example, United seems to use all their 737s interchangeably on most routes, and many airlines alter aircraft frequently from what was scheduled. Hopefully this is a good starting point
IAD Contracts IRL:
Country
- Airline:
Gates used: ## - Airline Code, Destination ID, Aircraft used
Aruba 
:
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA AUA B738/B739/B39M
Austria 
:
- Austrian Airlines:
Gates: B41 - OS VIE B76W
Bahamas 
:
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA NAS A320/B737/B738/B739
Barbados 
:
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA BGI B737/B738
Belgium 
:
- Brussels Airlines:
Gates: R9 - SN BRU A333
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA BRU B77W
Brazil 
:
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA GRU B764
Canada 
:
- Air Canada:
Gates: Z10 - AC YVR B38M
- Air Canada Express:
Gates: Z9 - AC YUL CRJ9
- AC YUL E175
- AC YYZ CRJ9
- Porter Airlines:
Gates: A19 - PD YTZ DH8D
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA YVR B738/B38M
- UA YYC A319/B738
- United Express:
Gates: 1G, C18, C20, D23, D25 - UA YOW CRJ7
- UA YUL E170/E175
- UA YYZ E170/E175
- WestJet:
Gates: B75, B79 - WS YYC B737/B738
Cayman Islands 
:
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - GCM B738
- GCM B739/B39M
China 
:
- Air China:
Gates: A32, R11 - CA PEK B77W (IAD-LAX-PEK-IAD)
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA PEK B788
Colombia 
:
- Avianca S.A.:
Gates: B48 - AV BOG A319/A320/A20N
Costa Rica 
:
- Avianca S.A.:
Gates: B48 - AV SJO A320
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA SJO B738/B38M
Denmark 
:
- SAS:
Gates: B38/B40 - SK CPH A21N/A333
Dominican Republic 
:
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA PUJ B738/B739
Egypt 
:
- Egyptair:
Gates: B38/B40 - MS CAI B77W/B789
El Salvador 
:
- Avianca S.A.:
Gates: B48 - AV SAL A320/A20N
- SalamAir:
Gates: ? - OV SAL A320
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA SAL B738/B38M
- Volaris El Salvador:
Gates: A31-A32, B37 - Y4 SAL A20N
Ethiopia 
:
- Ethiopian Airlines:
Gates: B37 - ET ADD A359/B77L/B77W/B789
France 
:
- Air France:
Gates: A23/A25 - AF CDG A359/B772/B77W
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA CDG B763/B764/B772
Germany 
:
- Lufthansa:
Gates: B45/B47 - LH FRA A343/A346/B744/B748
- LH MUC A346/A359/A388
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA FRA B772/B77W
- UA MUC B763/B764
Ghana 
:
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA ACC B788
Greece 
:
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA ATH B788
Guatemala 
:
- Avianca S.A.:
Gates: B48 - AV GUA A320/A20N
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA GUA B738/B38M
Iceland 
:
- Icelandair:
Gates: B41/B43 - FI KEF B38M/B39M
- Play Airlines:
Gates: A24 - OG KEF A20N
India 
:
- Air India:
Gates: B45/B47 - AI DEL B788
Ireland 
:
- Aer Lingus:
Gates: B75 - EI DUB A21N/A333
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA DUB B752
Israel 
:
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA TLV B788
Italy 
:
- ITA Airways:
Gates: A32 - AZ FCO A332
- Ethiopian Airlines:
Gates: B37 - ET FCO A359/B789 (ADD-FCO-IAD)
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA FCO B763/B788
Jamaica 
:
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA MBJ B738/B739
Japan 
:
- ANA:
Gates: B41/B43 - NH HND B789
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA HND B772
Jordan 
:
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA AMM B788
Mexico 
:
- Aeromexico:
Gates: ? - AM MEX B738/B38M
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA MEX A319/A320/B738/B739/B39M
Morocco 
:
- Royal Air Maroc:
Gates: A31 - AT CMN B788/B789
Netherlands 
:
- KLM:
Gates: A15 - KL AMS A332/A333
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA AMS B788
Nigeria 
:
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA LOS B788
Panama 
:
- COPA Airlines:
Gates: A15, A19, A24 - CM PTY B738/B39M
Portugal 
:
- TAP Air Portugal:
Gates: B50 - TP LIS A21N
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA LIS B752/B764
Puerto Rico 
:
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA SJU B737/B738/B38M/B739/B39M
Qatar 
:
- Qatar Airways:
Gates: A15, A23/A25, A32, B37 - QR DOH A359/A35K/B77W
Saudi Arabia 
:
- Saudia:
Gates: A31 - SV JED B772/B773
- SV RUH B773
Sint Maarten 
:
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA SXM B737
South Africa 
:
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA CPT B772/B789
South Korea 
:
- Korean:
Gates: A32 - KE ICN B77W
Spain 
:
- Iberia:
Gates: B37 - IB MAD A332
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA BCN B764/B772
- UA MAD B764
Switzerland 
:
- SWISS:
Gates: B49/B51 - LX ZRH A333
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA GVA B763
- UA ZRH B763/B764
Togo 
:
- Ethiopian Airlines:
Gates: B37 - ET LFW B788/B789 (IAD-LFW-ADD)
Türkiye 🇹🇷 :
- Turkish Airlines:
Gates: B37-B38/B40 - TK IST A359/B77W/B789
Turks and Caicos 
:
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA PLS B738/B739
U.S. Virgin Islands 
:
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA STT B737
United Arab Emirates 
:
- Etihad:
Gates: A14/A16 - EY AUH B789
- Emirates:
Gates: B42/B44 - EK DXB A388/B77W
United Kingdom 
:
- British Airways:
Gates: B42/B44 - BA LHR A388/B772/B77W/B788/B789/B78X
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA EDI B752
- UA LHR B763/B772
- Virgin Atlantic:
Gates: A32 - VS LHR A333/A339/B789
United States 
:
Alabama 
:
- United Express:
Gates: A2A-A6E - UA HSV E145
- UA MOB E145
Alaska 
:
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA ANC B38M
Arizona 
:
- Southwest Airlines:
Gates: B50, B64, B66 - WN PHX B737/B738/B38M
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA PHX B738/B38M/B739/B39M
California 
:
- Air China:
Gates: A32, R11 - CA LAX B77W (IAD-LAX-PEK-IAD)
- Alaska Airlines:
Gates: B63, B65, B67 - AS LAX B738/B38M/B39M
- AS SAN B739/B39M
- AS SFO B737/B738/B739/B39M
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA LAX B738/B38M/B739/B39M
- UA SAN B738/B38M/B739/B39M
- UA SFO B738/B38M/B739/B39M
- UA SMF A319/A320/B737/B738/B739
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA LAX B753
- UA SAN B772
- UA SFO B772/B77W/B788
Colorado 
:
- Southwest Airlines:
Gates: B50, B64, B66 - WN DEN B737/B738/B38M
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA DEN B738/B38M/B739/B39M
- UA DEN B753/B772
Connecticut 
:
- Avelo Airlines:
Gates: ? - XP HVN B737
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA BDL A320/B738/B38M/B739/B39M
- United Express:
Gates: A2A-A6E - UA BDL E175
Florida 
:
- Allegiant Air:
Gates: B62 - G4 JAX A320
- G4 PGD A320
- G4 SRQ A320
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA EYW B737
- UA FLL B738/B38M/B739/B39M
- UA JAX B737/B738/B38M/B739/B39M
- UA MCO B738/B38M/B739/B39M
- UA MIA B738/B38M/B739/B39M
- UA RSW B738/B38M/B739/B39M
- UA SRQ A319
- UA TPA B738/B38M/B739/B39M
- United Express:
Gates: A2A-A6E - UA JAX E175
- UA PBI E175
Georgia 
:
- Delta Air Lines:
Gates: B72, B74, B76, B78 - DL ATL A319/A320/A321/BCS3/B712/B738
- SkyWest Charter:
Gates: A2A-A6E - CW ATL CRJ2 (charter)
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA ATL A320/B737/B738/B38M/B739/B39M
- United Express:
Gates: A2A-A6E - UA SAV E145/E175
Hawaii 
:
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA HNL B764
Illinois 
:
- Southwest Airlines:
Gates: B50, B64, B66 - WN MDW B738/B38M
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA ORD A319/A320/B738/B38M/B739/B39M
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA ORD B752/B788
Indiana 
:
- FedEx:
Gates: X1 - FX IND A306 (cargo)
- FX IND B763 (cargo)
- United Express:
Gates: A2A-A6E - UA IND E170/E175
Kansas 
:
- United Express:
Gates: A2A-A6E - UA MCI E175
Kentucky 
:
- United Express:
Gates: A2A-A6E - UA SDF E175
- UPS:
Gates: Taxiway Z3 Ramp - 5X SDF B763 (cargo)
- 5X SDF MD11 (cargo)
Louisiana 
:
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA MSY A319/A320/B737/B738/B38M/B739/B39M
Maine 
:
- United Express:
Gates: A2A-A6E - UA PWM E170/E175
Massachusetts 
:
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA BOS A319/A320/B737/B738/B38M/B739/B39M
Michigan 
:
- Delta Air Lines:
Gates: B72, B74, B76, B78 - DL DTW A319/B712
- Delta Connection:
Gates: B72, B74, B76, B78 - DL DTW CRJ9/E175
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA PTK B739
- United Express:
Gates: A2A-A6E - UA DTW E175
Minnesota 
:
- Delta Connection:
Gates: B72, B74, B76, B78 - DL MSP E175
- SkyWest Charter:
Gates: A2A-A6E - CW MSP CRJ2 (charter)
- Sun Country Airlines:
Gates: B49/B51 - SY MSP B738
- United Express:
Gates: A2A-A6E - UA MSP E175
Missouri 
:
- United Express:
Gates: A2A-A6E - UA STL CRJ7
Montana 
:
- United Express:
Gates: A2A-A6E - UA BZN E175
Nevada 
:
- Southwest Airlines:
Gates: B50, B64, B66 - WN LAS B737
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA LAS B738/B38M/B739/B39M
New Jersey 
:
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA EWR A319/A320/B738/B38M/B739/B39M
- United Airlines:
Gates: C1-C8, C11-C17, C19, C27, D3, D5, D15, D21-D23, D26, D29-D32 - UA EWR B752
- United Express:
Gates: A2A-A6E - UA EWR E175
New York 
:
- Delta Connection:
Gates: B72, B74, B76, B78 - DL JFK CRJ9/E175
- SkyWest Charter:
Gates: A2A-A6E - CW JFK CRJ2 (charter)
- United Express:
Gates: A2A-A6E - UA ALB E145
- UA BUF E145/E170/E175
- UA JFK E175
- UA LGA E170/E175
- UA ROC E145/E175
- UA SYR E145
North Carolina 
:
- American Eagle:
Gates: B67, B71 - AA CLT CRJ9
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA CLT A320/B738/B38M/B739/B39M
- UA RDU B738/B38M/B739/B39M
- United Express:
Gates: A2A-A6E - UA CLT E175
- UA MYR E145
- UA RDU E175
Ohio 
:
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA CLE B737/B738/B38M/B739/B39M
- United Express:
Gates: A2A-A6E - UA CLE E145/E175
- UA CMH E175
- UA CVG E145/E170/E175
- UA DAY E145
Oregon 
:
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA PDX A319/B737/B738/B38M
Pennsylvania 
:
- SkyWest Airlines:
Gates: A2A-A6E - OO JST CRJ2 (United Airlines codeshare)
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA PIT B739
- UA SCE B737
- United Express:
Gates: A2A-A6E - UA AVP E145
- UA JST CRJ2 (sometimes SkyWest aircraft)
- UA MDT E145
- UA PHL E175
- UA PIT CRJ7/E145/E170/E175
Rhode Island :
- SkyWest Charter:
Gates: A2A-A6E - CW PVD CRJ2 (charter)
- United Express:
Gates: A2A-A6E - UA PVD CRJ7/E145/E175
South Carolina 
:
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA CHS A319/B738/B38M
- United Express:
Gates: A2A-A6E - UA CAE E145
- UA CHS E170/E175
Tennessee 
:
- Allegiant Air:
Gates: B62 - G4 BNA A320
- FedEx:
Gates: X1 - FX MEM B752/B763 (cargo)
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA BNA A320/B738/B38M/B739/B39M
- United Express:
Gates: A2A-A6E - UA TYS E145
Texas 
:
- Allegiant Air:
Gates: B62 - G4 AUS A319
- American Airlines:
Gates: B73 - AA DFW A321/B738
- American Eagle:
Gates: B67, B71 - AA AUS E175
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA AUS A319/A320/B737/B738/B38M/B739/B39M
- UA DFW A319/A320/B737/B738/B38M/B739/B39M
- UA IAH A320/B737/B738/B38M/B739/B39M
- UA SAT A320/B738/B38M/B739/B39M
- United Express:
Gates: A2A-A6E - UA AUS E170/E175
- UA DFW E175
- UA SAT E175
Utah 
:
- Delta Air Lines:
Gates: B72, B74, B76, B78 - DL SLC B739
Vermont :
- United Express:
Gates: A2A-A6E - UA BTV E145/E170/E175
Virginia 
:
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - UA ORF A320/B738
- United Express:
Gates: A2A-A6E - United Airlines CHO E145
- United Airlines ORF CRJ7/E145/E175
- United Airlines RIC CRJ7/E145
- United Airlines ROA E145/E175
- UPS:
Gates: Taxiway Z3 Ramp - 5X RIC B763 (cargo)
Washington 
:
- Alaska Airlines:
Gatesw: B63, B65, B67 - Alaska Airlines SEA B738/B739/B39M
- Delta Air Lines:
Gates: B72, B74, B76, B78 - Delta Airlines SEA BCS3
- United Airlines:
Gates: C9, C18, C23, C25, C28, D1-D2, D4, D6-D14, D16, D18-D20, D24 - United Airlines SEA B737/B738/B38M/B739/B39M