It was the site of a major battle during World War II between the Japanese and British forces which consisted of troops from India, Australia and Great Britain.

The population is estimated at 100,000, and consists of Malays, Chinese, Malaysian Indians (mostly Tamil) and Orang Asli, the indigenous people of Peninsular Malaysia.

Primary and secondary education are provided by a few schools in Slim River, namely: The waterfall at Sungai Bil is famous among the locals for a weekend getaway.

Several outdoor extreme sports are available inside Ulu Slim, reservation will be required for these activities such as white water rafting, 4x4 rides, camping, and jungle trekking.

It is accessible by road from the capital city, Kuala Lumpur (100 km) or by train (Slim River railway station).

Before the construction of North–South Expressway, all traffic going to destinations in the northern states of Peninsular Malaysia, such as Kedah, Perlis and Penang would pass through the town of Slim River.