- 1901 — Oil is discovered in Louisiana.
- 1904 — St. Rose Plantation, located near St. Rose Avenue, is demolished.
- 1911 — George Cousin’s Lumber Camp is established behind Lakewood West Subdivision.
- 1912 — The Hymelia Crevasse begins on May 14 at 6:30 p.m. near the St. Charles/St. John parish line.
- 1912 — On November 11, a massive train wreck occurs in Montz.
- 1914 — World War I begins.
- 1914 — Destrehan Plantation property is sold to Mexican Petroleum Company for the establishment of an oil refinery.
- 1915 — The “Great West Indian Hurricane” ravages south Louisiana on September 28.
- 1916 — The New Orleans Refining Company acquires Good Hope Plantation property to establish a marine petroleum supply terminal.
- 1917 — First Flood Control Act enacted as a result of Bonnet Carré, Hymelia, and other crevasses.
- 1917 — Congress declares war against Germany.
- 1917 — After 27 years of interdiction, St. Charles Borromeo Church Parish is reinstated to the diocese.
- 1918 — After 41 years of closure due to fire and interdiction, Red Church is assigned Father John Basty as pastor.
- 1918 — Louisiana Legislative Act 114 bans use of the German language in churches, schools, and newspapers.
- 1918 — Cousin’s Lumber Camp closes.
- 1919 — Carson Petroleum begins operating on the site of old Cedar Grove Plantation, St. Rose.
- 1921 — Present-day St. Charles Borromeo Church is built; old Red Church is torn down in the later twenties.
- 1921 — The courthouse is renovated and expanded.
- 1922 — Cities Service Oil Company begins operating in St. Rose at Carson site.
- 1923 — Bank of Hahnville is established.
- 1924 — Destrehan and Hahnville Public High Schools are established for white students.
- 1925 — General American Tank Storage Terminal and General American Transportation Company begin operation in Good Hope.
- 1927—The Great Mississippi River Flood affects the nation and initiates planning for construction of the Bonnet Carré Spillway.
- 1927—Prospect Plantation (Good Hope) is torn down in a levee setback project.
- 1928 — Flood Control Act of 1928 marks the beginning of the end to serious flooding in the Lower Mississippi Valley.
- 1929 — Bank of Good Hope is established.
- 1929 — Bonnet Carré Spillway construction begins in July.
- 1929 — The Great Depression begins in October.
- 1929 — St. Charles Borromeo Elementary School opens in Destrehan as the first private, parochial school in the parish.
- 1929 — Shell Petroleum Corporation, forerunner of Shell Oil Company, acquires the New Orleans Refining Company facility and it becomes Shell Norco Refinery.
- 1933 — The federal government establishes the Civilian Conservation Corps (CCC).
- 1935 — Colonial Dairy opens in Taft and becomes one of the largest dairies in Louisiana.
- 1935 — Dr. John Earle Clayton builds Claytonia, a large and stately residence north of Airline Highway in Norco.
- 1935 — The federal government establishes the Works Progress Administration (WPA).
- 1936 — Bonnet Carré Spillway is completed.
- 1937 — President Franklin Roosevelt visits the spillway project in Norco.
- 1938 — Fire destroys Alice Plantation in Ama.
- 1938—The Mississippi River levee setback claims riverfront properties in Luling.
- 1938 — Texaco drilling operations in Paradis Field begins.
- 1938 — Bayou Des Allemands Oil Field is discovered.
- 1939 — Paradis Oil Field is discovered.
- 1939 — World War II begins.
- 1941 — The United States enters World War II as Pearl Harbor is bombed by Japan.
- 1948 — St. Charles Borromeo High School opens in Destrehan.
- 1949 — St. Charles Parish Waterworks District I is created by the police jury.
- 1950 — Korean War begins in June.
- 1951 — Bethune High School in Norco and Carver High School in Hahnville are established for black students.
- 1952 — Lion Oil Company begins construction of its facility in Luling and merges with Monsanto in 1955.
- 1955 — Shell Chemical Company opens in Norco.
- 1955 — First parish library opens in Hahnville as a “demonstration library.” Charlotte Gaylord serves as the first librarian.
- 1957 — Edward A. Dufresne, Sr., builds Esperanza Plantation House in Luling. It remains a working plantation (2010) on which sugarcane has been grown since circa 1763.
- 1958 — American Oil Company closes its refinery in Destrehan.
- 1959 — Earl K. Long visits the parish.
- 1960—Bunge Grain Elevator opens.
- 1960—The Louisiana legislature establishes the South Louisiana Port Commission authorizing management of a public deep-draft port on the Mississippi River for the three river parishes: St. Charles, St. James, and St. John the Baptist.
- 1961 — United States special military force build-up begins in Vietnam.
- 1962—Local independent union at Shell Oil Company strikes and later joins the Oil, Chemical and Atomic Workers (OCAW), a national union.
- 1964 — President Lyndon Baines Johnson signs the Civil Rights Act of 1964.
- 1965 — First United States combat troops arrive in Vietnam.
- 1965 — Hurricane Betsy devastates south Louisiana. St. Charles Parish is ravaged and a tragic fire destroys Claytonia in Norco during the storm.
- 1965 — Our Lady of the Holy Rosary Church moves from Taft to Hahnville.
- 1966 — Union Carbide Company, now Dow–St. Charles Operations, opens in Taft on the site of the old Providence and Star Plantations.
- 1966 — Hooker Chemical, now Occidental Chemical, purchases the old Colonial Dairy site.
- 1968 — The River Road Historical Society is organized with the purpose of preserving and restoring Destrehan Plantation. Foundress Wayne Gaupp serves as the first president of the historical society.
- 1969 — Parish public schools are integrated.
- 1970 — Bunge Grain Elevator in Destrehan explodes, killing one and severely injuring two others.
- 1971 — American Oil Refinery donates the deteriorating Destrehan Plantation house to the River Road Historical Society.
- 1973 — All bays of the Bonnet Carré Spillway are opened to avoid major flooding downriver.
- 1973 — Perriloux Plantation in Montz is torn down in a levee setback project.
- 1973 — St. Charles Borromeo Parish celebrates its 250th anniversary.
- 1974 — Luling/Destrehan Bridge construction begins.
- 1974 — Waterford III Nuclear Power Plant permitted for construction on the site of the former Waterford Plantation.
- 1974 — Voters approve a new Louisiana Constitution.
- 1976 — The parish celebrates America’s bicentennial; President Gerald Ford visits the parish.
- 1976 — The new Destrehan and Hahnville High Schools open.
- 1976 — On October 20, the Frosta, a Norwegian freighter, hits the George Prince ferry as it crosses the river from Destrehan to Luling.
- 1976 — The new courthouse opens and the old courthouse is demolished.
- 1977 — Voters approve the St. Charles Parish Home Rule Charter.
- 1977–78 — West and east regional libraries are built.
- 1978 — Implementation of the new Home Rule Charter government begins on January 7.
- 1980 — The first parish president and council members assume office on June 2.
- 1983 — Luling/Destrehan Bridge opens on October 6 as the first cable-stayed structure to cross the Mississippi River with the longest cable-stayed span in the United States.
- 1983 — Ferry service is discontinued on November 13.
- 1983 — Good Hope Refinery conducts a major buyout of homeowners’ property in the town of Good Hope.
- 1984 — Luling/Destrehan Bridge is officially dedicated as the Hale Boggs Bridge by Act 346 of the 1984 Louisiana legislature.
- 1985 — Hurricane Juan causes major flooding in the parish.
- 1985 — Waterford III Nuclear Power Plant at Taft opens on September 26.
- 1988 — The May 5 catalytic converter (“cat cracker”) explosion at Shell Oil Refinery in Norco impacts most parish communities.
- 1990 — St. Charles Borromeo Parish celebrates the 250th anniversary of its patron saint.
- 1992 — Hurricane Andrew causes extensive damage to southeast Louisiana.
- 1995 — Record rainfall on May 8, referred to as a five-hundred year flood, inundates St. Charles and surrounding parishes.
- 1996 — St. Charles Historical Foundation is established.
- 1996 — The Olympic Torch passes through St. Charles Parish on the way to Atlanta.
- 1997—Construction begins below Luling on the Davis Freshwater Diversion Structure.
- 1998 — Shell Norco Museum opens.
- 1999 — Denver and Champion historic luggers (cypress boats) are donated to the parish by the Victor Matherne Family of Des Allemands.
- 2001 — On September 11, terrorist attacks on the East Coast paralyze the nation.
- 2001 — Two Catholic pastors from St.Charles Borromeo and St.Gertrude drown in a boating accident.
- 2002 — The Shell buyout of Diamond and other Norco properties is finalized.
- 2003 — Valero, a Fortune 500 diversified energy corporation, opens in the parish with the purchase of the defunct Orion Refinery.
- 2003 — The Louisiana Purchase Bicentennial is celebrated in St.Charles Parish.
- 2003 — The German Coast Farmers Market opens on June 7.
- 2005 — Hurricane Katrina strikes southeast Louisiana and the Mississippi Gulf Coast on August 29. Several weeks later, Hurricane Rita wrecks havoc on southwest Louisiana.
- 2007 — The St. Charles Museum and Historical Association is established from the merger of River Road Shell Museum and St. Charles Historical Foundation.
- 2007 — The two-hundredth anniversary of the civil parish of St.Charles Parish is celebrated on March 31.
