The following command creates a bucket named my-bucket:

aws s3api create-bucket --bucket my-bucket --region us-east-1

Output:

{
    "Location": "/my-bucket"
}

The following command creates a bucket named my-bucket in the eu-west-1 region. Regions outside of us-east-1 require the appropriate LocationConstraint to be specified in order to create the bucket in the desired region:

$ aws s3api create-bucket --bucket my-bucket --region eu-west-1 --create-bucket-configuration LocationConstraint=eu-west-1

Output:

{
    "Location": "http://my-bucket.s3.amazonaws.com/"
}