Good Morning America ran a segment earlier this month regarding ufo sightings in America. They detailed the Top 10 States by number with reported ufo sightings. They also listed the place and the date where the last sighting was in that state.
The top three states with reported UFO sightings were California (11,202), Florida (5,113) and Washington (5,004). Each state also reported a sighting in March of this year. The article is from earlier in April so we can just guess there have been reported sightings in April as well. You can read the blurb for each sate at the source.