Please identify all the named entities mentioned in the input sentence provided below. Use only the categories: PER - person, ORG - organization, and LOC - location.
Remember, nationalities are neither locations nor organizations, and organizations can represent other groups of people.
Pay attention to the provided example. You should only output the results in JSON format, following a similar structure to the example result provided.

Example sentence and results:

“While much of the digital transition is unprecedented in the United States, the peaceful transition of power is not,” Obama special assistant Kori Schulman wrote in a blog post Monday.

"Results": [
    {
        "TypeName": "LOC",
        "Text": "United States",
        "Start": 62,
        "End": 75
    },
    {
        "TypeName": "ORG",
        "Text": "Obama",
        "Start": 119,
        "End": 124
    },
    {
        "TypeName": "PER",
        "Text": "Kori Schulman",
        "Start": 143,
        "End": 156
    }
]

Considering the input sentence below, what is the output result?

The feasibility study estimates that it would take passengers about four minutes to cross the Potomac River on the gondola.


"Results": [
    {
        "TypeName": "LOC",
        "Text": "Potomac River",
        "Start": 94,
        "End": 107
    }
]