How to load multiple files (same schema) into a table in BigQuery?

If using cloud storage is an option, you can put them all in a common prefix in a bucket and use a wildcard e.g. gs://my_bucket/some/path/files* to specify a single load job with multiple inputs quickly.

Note that

You can use only one wildcard for objects (filenames) within your bucket. The wildcard can appear inside the object name or at the end of the object name. Appending a wildcard to the bucket name is unsupported.

so something like gs://my_bucket/some/*/files* is not supported.

Source: https://cloud.google.com/bigquery/docs/loading-data-cloud-storage#load-wildcards