Question: When was the 2016 Oregon Rebulican primary held?

Context articles: Republican Party presidential primaries, 2016
Oregon Democratic primary, 2016
Allen Alley
Oregon Republican primary, 2016
Louisiana gubernatorial election, 1912
Texas Democratic primary and caucuses, 2008
Louisiana gubernatorial election, 1932
Louisiana gubernatorial election, 1916
El Paso, Texas mayoral election, 2013
Louisiana gubernatorial election, 1908

The 2016 Republican Party presidential primaries and caucuses were a series of electoral contests taking place within all 50 U.S. states, the District of Columbia, and five U.S. territories, occurring between February 1 and June 7.
 Sanctioned by the Republican Party, these elections are designed to select the 2,472 delegates to send to the Republican National Convention, who selected the Republican Party's nominee for President of the United States in the 2016 election, Donald Trump.
 The delegates also approved the party platform and vice-presidential nominee.
The 2016 Oregon Democratic primary was held on May 17 in the U.S. state of Oregon as one of the Democratic Party's primaries ahead of the 2016 presidential election.
Allen Alley (born August 3, 1954) is an American businessman and Republican politician from the State of Oregon.
 He sought the Republican nomination for Governor of Oregon in the 2016 Oregon gubernatorial special election, losing to Bud Pierce.
 Alley also sought the Republican nomination in 2010, but lost to Chris Dudley.
 Alley was the Republican nominee for Oregon State Treasurer in 2008 and also served as Chairman of the Oregon Republican Party from January 2011 to February 2013.
The 2016 Oregon Republican primary was held on May 17 in the U.S. state of Oregon as one of the Republican Party's primaries ahead of the 2016 presidential election.
The Louisiana gubernatorial election of 1912 was held on April 16, 1912.
 Like most Southern states between Reconstruction and the civil rights era, Louisiana's Republican Party was virtually nonexistent in terms of electoral support.
 This meant that the Democratic Party primary held on January 23 was the real contest over who would be governor.
 The election resulted in the election of Democrat Luther E. Hall as governor of Louisiana.
The 2008 Texas Democratic primary and caucuses were a series of events to determine the delegates that the Texas Democratic Party sent to the 2008 Democratic National Convention.
 Delegates were selected using results from two sources: the Texas Presidential Primary held on March 4 by the Secretary of State of Texas's office, and a series of caucus events held between March 4 and June 7 by the Texas Democratic Party.
 The indecisive results of Super Tuesday, and the fact that Texas had the largest number of delegates among the states remaining on the Democratic primary calendar, resulted in the Texas primary receiving significant attention from both the Hillary Clinton and Barack Obama campaigns.
The Louisiana gubernatorial election of 1932 was held on January 19, 1932.
 Like most Southern states between the Reconstruction Era and the Civil Rights Movement, Louisiana's Republican Party had virtually no electoral support.
 This meant that the Democratic Party primary held on this date was the real contest over who would be governor.
 The election resulted in the election of Oscar K. Allen as governor of Louisiana.
 Louisiana was one of only two states that held the election on a date other than the first Tuesday following the first Monday of November.
The Louisiana gubernatorial election of 1916 was held on April 18, 1916.
 Like most Southern states between the Reconstruction Era and the Civil Rights Movement, Louisiana's Republican Party was virtually nonexistent in terms of electoral support.
 This meant that the Democratic Party primary held on January 25 was supposed to be the real contest over who would be governor.
 However, in this particular election Progressive Party nominee John M. Parker ran an unusually competitive campaign, garnering 37% of the general election vote.
 The election resulted in the election of Democrat Ruffin G. Pleasant as governor of Louisiana.
The 2013 El Paso mayoral election was held on June 8, 2013, to elect the Mayor of El Paso, Texas.
 Incumbent Mayor John Cook could not seek another term due to term limits.
 In the nonpartisan primary held on May 11, 2013, businessman Oscar Leeser and City Councilman Steve Ortega placed first and second with 47% and 21% of the vote, respectively, and because no candidate received a majority, a runoff election was held on June 15.
 Leeser won the runoff election.
The Louisiana gubernatorial election of 1908 was held on April 21, 1908.
 Like most Southern states between Reconstruction and the civil rights era, Louisiana's Republican Party had virtually no electoral support.
 This meant that the Democratic Party primary held on January 28 was the real contest over who would be governor.
 This election marked the first time Louisiana used primaries to nominate party nominees.
 The election resulted in the election of Democrat Jared Y. Sanders, Sr. as governor of Louisiana.