Geotargit and other services will tell you that there are 9 towns named Manhattan in the USA, but only 5 of them are towns of real consequence. The others are too small to matter much, and there are no population centers with this name outside of the United States.
One of the towns with Manhattan in its name is Manhattan Beach, CA. This community of about 35,000 in the LA area has no significant tourist attractions. Most of its recommended activities have to do with its beach and other beaches in the area.
Manhattan, IL is a stand alone town of about 7,000 just south of Chicago. There is not much to do there either, but there are a lot of attractions in Chicago. The other towns named Manhattan that are very tiny are in Mississippi, Pennsylvania, and Indiana. The town of Manhattan, NV has only 124 people living in it, and Manhattan, MT has a population of about 1,500.
The town of Manhattan reported to be in Florida has an interesting history. In 1925 a developer in the Tampa area proposed a community named Manhattan for this area. Since so many retirees came to Florida to live, this was not a half bad idea at the time. However, hurricanes happened and the town never got built. The idea was quickly abandoned, but it’s said that there is a subdivision with this name in the Tampa–St. Pete area. I have not confirmed this or studied the area for viable tourist activities.
Manhattan, KS is the 2nd largest Manhattan with 52,000 or so residents. Ruth and I used to go through Manhattan, Kansas a lot and were familiar with its tourist potential but we now live in the state of Washington and see less of Kansas. We have only been through Manhattan, KS a couple of times lately and it seems to have changed. The next time we make it to this area, however, I plan to check out the Flint Hills Discovery Center and the insect zoo at its university.
The largest Manhattan in the USA is, of course, the New York City borough with this name. The name Manhattan comes from the Munsee Lenape, a Native American tribe. It incorporates their words for bow and gathering and its usage dates from the 17th century. When people from Europe arrived on the island soon called Manhattan, they found many Native Americans already living there, and New York stayed one borough for more than 200 years. Now there are 5 boroughs. The 2nd one added was The Bronx in 1894. It was named for Jonas Bronck, a Swedish settler.
There are many activities for visitors in Manhattan, but fewer since COVID came to town, and the sturdy population of 1.6 million reported in 2019 is probably less now but no one know for sure until things settle down a bit.