The sentence that is written correctly is:
“On the way to Orlando, Florida, we saw an alligator.”
The other sentences either lack proper punctuation or require commas for clarity:
- “Our road trip across the country took us through Saint Louis, Missouri.” (It needs a comma after “Louis”.)
- “A kind family from Salina, Kansas, helped us fix it.” (It needs commas before and after “Kansas”.)
- “Halfway to Sandusky, Ohio, we had a flat tire.” (It needs a comma after “Ohio”.)