Title: State of the Union
Content:  Since 1966, the speech has been followed on television by a response or rebuttal by a member of the major political party opposing the president's party. The response is typically broadcast from a studio with no audience. In 1970, the Democratic Party put together a TV program with their speech to reply to President Nixon, as well as a televised response to Nixon's written speech in 1973. The same was done by Democrats for President Reagan's speeches in 1982 and 1985. The response is not always produced in a studio; in 1997, the Republicans for the first time delivered the response in front of high school students. In 2010, Virginia Governor Bob McDonnell gave the Republican response from the House of Delegates chamber of the Virginia State Capitol in Richmond, in front of about 250 attendees. In 2004, the Democratic Party's response was delivered in Spanish for the first time, by New Mexico Governor Bill Richardson. In 2011, Minnesota Congresswoman Michele Bachmann also gave a televised response for the Tea Party Express, a first for a political movement.
Title: Response to the State of the Union address
Content:  The response to the State of the Union address is a rebuttal speech, often brief, delivered by a representative (or representatives) of an opposition party following a presidential State of the Union address. When the president is a Democrat, the rebuttal is typically given by a Republican, and vice versa. The practice began in 1966 when Republican U.S. Senator Everett Dirksen (Illinois) and U.S. Representative Gerald Ford (Michigan) appeared on TV to offer a response to the address by Democratic President Lyndon Johnson. The opposition party's response has varied in format, ranging from a prerecorded 45-minute TV program in 1970 
Title: Response to the State of the Union address
Content:  1First organized, televised response to a presidential State of the Union message 2Denotes prerecorded program 3A focus group participated in this televised discussion
Title: Response to the State of the Union address
Content:  a call-in show in 1972 where a panel of congressmen answered unrehearsed questions from callers. Since the late 1980s, it usually has been a televised speech given soon after the State of the Union address. Three people have given both a response and a State of the Union address: Democrat Bill Clinton and Republicans Gerald Ford and George H. W. Bush. That group is expected to grow to four people when 46th President Joe Biden (who took part in the Democratic responses in 1983 and 1984 as a Senator) makes the first State of the Union address of his presidency.
Title: Response to the State of the Union address
Content:  In addition to responses to official State of the Union addresses, there have been five official responses to non–State of the Union speeches which were delivered soon after presidential inaugurations.
Title: State of the Union
Content:  1953 and 1961, Congress received both a written State of the Union message from the outgoing president and a separate State of the Union speech by the incoming president. Since 1981, in recognition that the responsibility of reporting the State of the Union formally belongs to the president who held office during the past year, newly inaugurated presidents have not officially called their first speech before Congress a "State of the Union" message.  Warren Harding's 1922 speech was the first to be broadcast on radio, albeit to a limited audience, while Calvin Coolidge's 1923 speech was the first to be 
Title: State of the Union
Content:  Ronald Reagan's 1986 State of the Union Address was the first to have been postponed. He had planned to deliver the speech on January 28, 1986, but it was delayed for a week following the Space Shuttle Challenger disaster that morning. Reagan instead addressed the nation from the Oval Office about the disaster. In 1999, Bill Clinton became the first president to deliver an in-person State of the Union address while standing trial for impeachment; the speech occurred the same day that Clinton's defense team made its opening statement, though he did not mention the proceeding. On January 23, 2019, 
Title: 2013 State of the Union Address
Content:  Senator Marco Rubio a Republican of Florida, delivered the official Republican response to the 2013 State of the Union Address. Kentucky Republican Senator Rand Paul delivered the Tea Party's rebuttal to Obama's 2013 State of the Union Address. The BBC reported reactions from US newspapers such as the New York Times and the Washington Post. Additional reactions from US newspapers was gathered by the website al.com. The official Libertarian response was given by Carla Howell, the Executive Director of the Libertarian National Committee. The official Green Party response was given by Jill Stein, the party's 2012 presidential candidate.
Title: State of the Union
Content:  In the State of the Union address, the President traditionally outlines the administration's accomplishments over the previous year, as well as the agenda for the coming year, often in upbeat and optimistic terms. It has become customary to use the phrase "The State of the Union is strong," sometimes with slight variations, since President Ronald Reagan introduced it in his 1983 address. It has been repeated by every president in nearly every year since, with the exception of George H. W. Bush. Gerald Ford's 1975 address had been the first to use the phrasing "The State of the Union is...", though Ford completed the 
Title: State of the Union
Content:  report to Congress. After 1913, Woodrow Wilson, the 28th U.S. President, began the regular practice of delivering the address to Congress in person as a way to rally support for the president's agenda. With the advent of radio and television, the address is now broadcast live across the country on many networks. Since 1934 during the first term of Franklin D. Roosevelt, the 32nd U.S. President, the State of the Union has typically been given in January. In 1981, Ronald Reagan, the 40th U.S. President, began the practice of newly inaugurated presidents instead delivering an address to Congress in February of the first year of their term, but not designating that speech as an official "State of the Union".

Question: when did response to state of the union start?
Answer: in 1966.
1966.