An analysis of the Robert F. Kennedy, Jr vote shows that he received his highest percentages in counties that were more pro-Trump than that state as a whole. However, he also received his very highest support in counties with a Native American majority, and those counties were more pro-Harris, so the two factors must be weighed together to determine if his presence in the race helped either Trump or Harris.
Kennedy has long been intensely interested in Native American welfare, and Native Americans have long admired him for that. When Kennedy announced his vice-presidential nominee in Oakland, California, Native American speakers and performers were an important part of the meeting.
In the 22 counties with a Native American majority, and in which Kennedy was on the ballot, he received 2.49% of the total vote. This contrasts the the nation as a whole, in which he only received .98% of the vote in the states where he was on the ballot.
A large majority of the Native American vote went for Harris, despite some early news reports that reported the opposite. See this analysis from the Brookings Institution.
Setting aside the relatively small number of Native American-majority counties, one sees that in a large majority of states in which Kennedy was on the ballot, his best county in that state was a county that was more pro-Trump than that state as a whole. This tends to show that Kennedy’s support came at the expense of Trump.
Kennedy was on the ballot in 30 states. In four of them his best county was a Native American-majority county (Alaska, Montana, New Mexico, and South Dakota). Setting those aside, one finds that in 21 states Kennedy’s strongest county was a county that was more pro-Trump than that state as a hole. In only five states was the best Kennedy county a county that was more pro-Harris than that state as a whole. Those five states were Alabama, Arkansas, Colorado, Mississippi, and Rhode Island.
Alaska has no counties, so this analysis substitute state representative districts for Alaska. Kennedy’s best “county” was Alaska’s 38th State House District, which could be named “Bethel”, and where Kennedy got 5.58% of the vote.