As of the 2010 United States Census, the district had a population of 215,874, of whom 160,293 were of voting age. The racial makeup of the district was 169,062 White, 7,645 African American, 295 Native American, 27,528 Asian, 59 Pacific Islander, 6,450 from some other race, and 4,835 from two or more races. Hispanic or Latino of any race were 22,856 of the population. The district had 166,349 registered voters as of February 1, 2020, of whom 66,875 were registered as unaffiliated, 57,077 were registered as Democrats, 40,962 were registered as Republicans, and 1,435 were registered to other parties. Home ownership was high as was the percentage of college graduates. District residents were comparatively wealthy, with high incomes and property values that have resulted in low municipal and other property taxes. The district has low numbers of African-Americans, the elderly and poor children. Prior to the 2011 apportionment, registered Republicans outnumbered Democrats by a 2 to 1 margin. Throughout most of the district's history, Republicans held a strong grip in winning elections with the district electing only Republican legislators for over 40 years, one of two in the state. However, in the 2011 redistricting, the addition of Princeton and South Brunswick brought in more Democrats to the district with the district electing its first Democrat, Andrew Zwicker, in 2015.
Long-time Senator Raymond Bateman ran for Governor of New Jersey in 1977, losing to Brendan Byrne, with John H. Ewing taking Bateman's seat in the Senate and Elliott F. Smith taking Ewing's former seat in the Assembly. Smith did not run for re-election in 1983 and his Assembly seat was won by John S. Penn. After five terms in office, Penn did not run for re-election in 1993 and was replaced by Christopher "Kip" Bateman. John Ewing chose not to run for re-election in 1997 after 30 years in the legislature. He was replaced in the Senate by Walter J. Kavanaugh, with Peter J. Biondi elected to Kavanaugh's former seat in the Assembly. Ewing remarked that "Dear Walter has been waiting and waiting to take my place... he keeps threatening to push me in front of a bus". Kip Bateman moved up to the Senate to fill the seat vacated by the retirement of Walter Kavanaugh in the 2007 elections. Peter Biondi won re-election and was joined in the Assembly by Denise Coyle, a member of the Somerset County Board of Chosen Freeholders. In 2011, Coyle declined to run for re-election as her Bernards Township home was moved out of the district and the seat was won by Jack Ciattarelli, a member of the Somerset County Board of Chosen Freeholders. Peter Biondi died two days after winning re-election, and was replaced by two appointments of the Republican County Committee members of the 16th district: Ciattarelli was appointed for the remainder of the 2010–2012 session and Readington Township committeewoman Donna Simon was appointed for the first part of the 2012–2014 session. Simon's appointment would only stand until a November 2012 special election; Simon faced Democrat Marie Corfield in the election to complete the remainder of the term. In the November 6 election which coincided with the general elections for President, U.S. Senate, and the House of Representatives, Simon defeated Corfield by just under 1,000 votes out of 91,000 ballots cast. Simon would be re-elected to a full term in 2013 with Ciattarelli but was defeated in 2015 in a close race by Democrat Andrew Zwicker in 2015. Initial counts showed Simon ahead of Zwicker on the night of the election but following the counting of provisional ballots, Simon conceded November 16. Senators and Assembly members elected from the district are as follows:
