Complex sentence: From 1990 until 2009, with the exception of 2006 due to extensive renovations, the race was held on Labor Day; in 2004, it was elevated to a Grade II event.
Split into simpler sentences: From 1990 until 2009, with the exception of 2006 due to extensive renovations, the race was held on Labor Day. In 2004, it was elevated to a Grade II event.