Every March, Chicago celebrates St. Patrick’s Day in one of the most iconic ways in the country: by dyeing the Chicago River bright green.
The tradition began in 1961 when members of the Chicago Journeymen Plumbers Local Union used green dye to detect illegal sewage discharges. After seeing how vividly the dye transformed the water, city leaders embraced the idea of turning the river green for St. Patrick’s Day. What started as a plumbing solution quickly became one of Chicago’s most recognizable annual events.
Today, the river dyeing draws thousands of spectators to downtown Chicago and marks the start of a full weekend of festivities. For visitors planning their St. Patrick’s Day weekend, pairing the river dyeing with a visit to Skydeck Chicago at Willis Tower offers a complete downtown experience, from the riverwalk to panoramic skyline views 103 floors above the city.
When Is the Chicago River Dyed Green?
The Chicago River is typically dyed green on the Saturday before St. Patrick’s Day each year.
In 2026, the Chicago River dyeing will take place on:
Saturday, March 14, 2026
The dyeing usually begins around 10:00 a.m. Central Time, several hours before the downtown St. Patrick’s Day Parade.
Because the event takes place in the morning, many visitors plan to arrive downtown early, watch the river transform, and then continue their day exploring Chicago’s Loop, including nearby attractions like Skydeck Chicago.
What Time Does the Chicago River Get Dyed?
The dyeing process generally begins at 10:00 a.m. and takes approximately 45 minutes to one hour to complete.
Boats release the environmentally safe dye into the Chicago River between Columbus Drive and State Street. Within minutes, the water turns a vivid emerald green.
If you want to see the river at its brightest, plan to be along the riverfront by mid-morning. After viewing the spectacle at street level, visitors can head to Skydeck Chicago for elevated skyline views during one of the city’s most festive weekends.
How Long Does the Chicago River Stay Green?
The bright green color typically lasts for about four to five hours.
When the tradition first began, the dye lingered for nearly a week. Today’s refined formula creates a dramatic but temporary effect, allowing the color to gradually fade by mid-to-late afternoon.
If you want to photograph the river at peak color, the best window is late morning through early afternoon. Many guests schedule a mid-day Skydeck visit after seeing the river to continue their St. Patrick’s Day experience with panoramic city views.
How Do They Dye the Chicago River Green?
The Chicago Journeymen Plumbers Local Union 130 oversees the dyeing each year.
Originally, 100 pounds of dye were used. Today, approximately 40 to 60 pounds of a plant-based, environmentally friendly dye are applied. The exact formula remains a closely guarded secret and is often referred to as “leprechaun dust.”
The dye is sprayed from boats and spreads quickly through the river, creating the signature green color that has become synonymous with Chicago’s St. Patrick’s Day celebration.
Where Can You See the Chicago River Dyed Green?
The dyeing takes place along the main branch of the Chicago River in downtown Chicago, primarily between Columbus Drive and State Street.
Popular viewing locations include:
- Chicago Riverwalk
- Upper and Lower Wacker Drive
- Downtown bridges
- Riverfront restaurants and rooftops
For a broader perspective of the celebration weekend, Skydeck Chicago provides sweeping views of downtown, the Chicago River corridor, and the city skyline. Located inside Willis Tower, Skydeck offers indoor access and timed entry, making it a comfortable addition to your St. Patrick’s Day itinerary, especially in unpredictable March weather.
Plan Your St. Patrick’s Day Weekend in Chicago
The river dyeing marks the beginning of a full day of celebration, including:
- The downtown St. Patrick’s Day Parade
- Neighborhood parades across Chicago
- Festive events throughout the city
Many visitors begin their morning along the river, explore downtown, and then experience the city from above at Skydeck Chicago. With views stretching across four states on clear days, Skydeck offers a memorable way to complete your St. Patrick’s Day visit.
Frequently Asked Questions About the Chicago River Dyeing
When is the Chicago River dyed green?
The river is typically dyed green on the Saturday before St. Patrick’s Day each year. In 2026, the dyeing will take place on Saturday, March 14.
What time does the Chicago River get dyed?
The dyeing usually begins around 10:00 a.m. Central Time and takes about 45 minutes to one hour.
How long does the Chicago River stay green?
The river remains bright green for approximately four to five hours before gradually fading.
What do they use to dye the Chicago River green?
The Chicago Journeymen Plumbers Local Union uses a plant-based, environmentally safe dye developed specifically for the event.
Where is the Chicago River dyed green?
The dyeing occurs along the main branch of the Chicago River in downtown Chicago, primarily between Columbus Drive and State Street.
What is the best way to plan a visit during the river dyeing?
Arrive early in the morning to watch the dyeing, then continue exploring downtown. Many visitors include a stop at Skydeck Chicago for panoramic skyline views during the St. Patrick’s Day weekend celebration.