Don't make us all laugh ;-) Eugene is a nice small town, but there are more people at LAX (airport) on any given weekday at 2 A.M. than in Eugene/Springfield.
The So Cal USATF Association dwarfs your little Oregon Assn by 100 times. A huge percentage of the total USATF membership are So Cal residents. Likewise, a huge percentage of Olympic and international medals are won by So Cal residents. On any given weekend in So Cal, there are dozens of high school meets, junior high school meets, juco meets, four year college meets, road races, master meets, cross country races, youth meets, triathlons, half-marathons, etc. The number of participants, fans, officials, etc. are 100 times that of Oregon. Rememeber that So Cal is warm all year around. The health clubs, gyms, beaches, trails are packed every day at all hours.
International and Olympic events have always been an amazing success in So Cal. The 1932 and 1984 Olympics were a total success. The FIFA mens and womens champs were record breakers. USC's 9 Football Natl Champs, UCLA's 11 Basketball NC, Dodgers 5 World Champs, Lakers 10 World Champs, Raiders 1 World Champs, annual Rose Bowl Game and Parade, etc. were all huge fan draws.
An L.A. IAAF WC or Olympics would be another guaranteed record breaker. For example, just a few weeks ago, the Lakers drew 93,000 fans to the L.A. Coliseum, and 2 million fans to the Lakers 15th World Championships Victory celebration.