Creating checkbox list

Try playing around with the style of the HTML div. This might work.

html.Div([
    dcc.Checklist(
        options=[
            {'label': 'New York City', 'value': 'NYC'},
            {'label': 'Montréal', 'value': 'MTL'},
            {'label': 'San Francisco', 'value': 'SF'}
        ],
        value=['MTL', 'SF']
    ), style={"width": '10%', 'display': "inline-block"}
])