From the DC / MPD website - if anyone is curious about whether to call 311 or 911. Or what services 311 (previously 727-1000) can help with.
(if you want police, fire or emergency medical services to respond to a location)
Any crimes in progress (or just occurred), especially if the suspect is still on the scene
Serious violent crimes such as homicide, robbery, domestic violence and assault
Gunshots or a person with a gun or other dangerous weapon
Vehicle crashes with personal injury, major property damage or traffic tie-ups
Illegally parked cars that are blocking traffic
Or if you see a criminal you know is wanted by the police
(for city services and police matters that do not require police to respond to a location
Property crimes no longer in progress, such as vandalism, thefts, graffiti, stolen autos and garage burglaries
Illegally parked vehicles, vehicles blocking driveways
Minor vehicle crashes with no injuries or traffic tie-ups
MPD phone numbers and addresses
All other city services, such as Public Works, Motor Vehicles, Human Services, and the Mayor's Office
Trash pick up problems
City agency phone numbers, addresses and hours of operations
You can also call (202) 737-4404 to report your non-emergency.
Please select a service from the list below. Then follow the step-by-step directions to complete the request. If the service you want is not listed, please visit DC.Gov's OnLine Services database or contact the Mayor's Citywide Call Center at 311, 24 hours a day, 365 days a year.
The following services were listed as problems you can call 311 about:
Abandoned Bicycles How Am I Driving Compliment Signs – Parking
Abandoned Vehicles Illegal Dumping Signs – Street Name
Alley Cleaning Litter Can Service or Repair Street Cleaning
Alley Lights Parking Enforcement Street Repair
Alley Repair Parking Meters Streetlight Repair
Autumn Leaf Collection Pavement Markings Supercan
Bulk Trash Collection Potholes Traffic Signals
Curb & Gutter Repair Rat Abatement Traffic Signs
Dead Animal Recycling Bin Trash Collection
Eviction Recycling Collection Tree Maintenance
Graffiti Residential Parking Permit Utility Cuts Repair
Grass & Weeds Mowing Sanitation Enforcement Vacant Lot
How Am I Driving Complaint Sidewalk Repair Vacant Lot
You can create an online ticket at http://dc.gov/registration/login.asp?appid=3&target=http%3A%2F%2Fsrc%2Edc%2Egov%2Fccc%cccValidateUserDefault%2Easp or Call 311.