This Presidential Primary coincides with a state/local primary. These coinciding primaries tend to have an impact upon voter turnout.

Tuesday 17 May 2016 (presumably): Oregon Primary. Hours end at 8:00p PDT (0300 UTC) / 8:00p MDT (0200 UTC). Oregon votes by mail. Ballots must be in the hands of election workers or in an official drop-off location no later than 8 PM local time. OREGON is the reverse of the norm because the by far largest portion of the state is in the lagging time zone and the networks have no choice but to not consider the OREGON polls closed until 8 PM Pacific. Delegate Selection: Proportional Primary. Voter Eligibility: Closed Primary.

Primary
Source: Oregon Secretary of State.
Status: Official. Retrieved: Friday 17 June 2016.
Included in Nationwide vote.

Tuesday 17 May 2016 (presumably): All 28 of Oregon's delegates to the Republican National Convention are allocated to presidential contenders based on the results of the voting in today's Presidential Primary.

• 28 (15 district, 10 at-large, 0 bonus, plus 3 party leader) delegates to the National Convention are to be bound to presidential contenders based on the primary vote statewide. Compute the number of delegates each candidate receives by taking 28 delegates × the candidate's statewide vote ÷ the total statewide and round down to the whole number. If too few delegates are allocated, round up those candidates with the largest remainders until all delegates have been allocated. [Special Rules for the ORP 7.6]

Primary
Source: Oregon Secretary of State.
Status: Official. Retrieved: Friday 17 June 2016.

Trump: 28 delegates × 252,748 ÷ 393,920 = 17.965 delegates. Round down to 17. Fraction: 0.965.
Cruz: 28 delegates × 65,513 ÷ 393,920 = 4.657 delegates. Round down to 4. Fraction: 0.657.
Kasich: 28 delegates × 62,248 ÷ 393,920 = 4.425 delegates. Round down to 4. Fraction: 0.425.
Trump, nearest to the rounding threshold (0.965 delegate), gains a delegate.
Cruz, nearest to the rounding threshold (0.657 delegate), gains a delegate.
Kasich, nearest to the rounding threshold (0.425 delegate), gains a delegate.

The 3 party leaders, the National Committeeman, the National Committeewoman, and the chairman of the Oregon's Republican Party, will attend the convention as bound delegates by virtue of their position.

This is a vote by mail primary. State election officials will be mailing ballots out to registered voters before the election; the voter has until 8 PM local time on the date of the Primary to return the completed ballot to either the county election office or a designated drop site -- postmarks do not count.

Saturday 4 June 2016 (presumably): District and State Conventions. District and Statewide (at-large) Delegates are elected according to the results of the primary.

Each person selected as a delegate ... shall sign a pledge that he/she shall vote at the National Convention for the candidate for the President of the United States he/she favors until the candidate is: (1) nominated; (2) receives less than 35% of the votes for nomination at the convention; (3) releases the delegate from the pledge; or (4) until two convention nominating ballots have been taken. Should a delegate ... refuse to cast his/her vote in accordance with this pledge ... the Chairman of the Oregon delegation ... shall report to the convention floor that delegate's vote in accordance with such laws and rules until such time as that delegate is released from his/her pledge. [Oregon Republican Party Bylaws ARTICLE XVII Section B.; State Law (ORS 248.315)]