A C182's engine quit during descent; the pilot declared an emergency and after landing safely on a highway discovered the fuel selector was not on both with fifteen gallons in the right tank. With the Highway Patrol's help he took off to his nearby destination.

Narrative

I was on a VFR flight descending from a cruise altitude of 8;500 MSL in preparation for landing. Shortly after beginning descent; I noticed a loss of power. I immediately established my best glide speed and began searching for a landing site. I was flying along a highway; and initially discounted landing on it due to traffic. I was unable to spot private airfields 4 miles north and 5 miles south of me; and decided to make my approach to a field west of an oval track. Taking a last look at the 2 lane highway; I noticed a gap in southbound traffic large enough to make a successful landing without interfering with them; and a single vehicle northbound I could land behind without endangering other northbound traffic. I successfully landed and exited the highway. I made a 'Mayday' call on Center frequency to advise of my emergency landing; and reported successfully landing without damage and asked ATC to advice Highway Patrol. After checking the engine for damage and finding nothing amiss; I 'stick' checked my fuel tanks in case I had burned fuel at a greater rate than expected. I was surprised to find the left tank empty while the right tank held 15 gallons. I looked at the fuel selector which I normally leave on the 'both' position and found I had selected left tank. Despite checking everything else to restart the engine; I failed to check the second thing on my emergency checklist...'FUEL ON BOTH'! After coordinating with the Highway Patrol officers who responded to stop traffic on the highway; I made an uneventful takeoff and continued into my destination airport; where I added 50.83 gallons (my aircraft holds 62 gallons usable and burns 12-13 gallons per hour).