Property, Plant, and Equipment, Net

Property, plant, and equipment, net were as follows:



	December 31,
(In thousands)	2019			2018
Buildings	$	18,570		$	18,799
Machinery and equipment	94,274			87,700
Tooling	32,267			29,575
Leasehold and building improvements	37,527			34,486
Software	25,910			25,406
Furniture and fixtures	3,905			2,572
Computer equipment	9,935			8,551
	222,388			207,089
Accumulated depreciation	(135,254		)	(116,805		)
	87,134			90,284
Construction in progress	3,598			5,556
Total property, plant, and equipment, net	$	90,732		$	95,840

Depreciation expense was $24.7 million, $26.4 million and $24.4 million for the years ended December 31, 2019, 2018, and 2017, respectively.

The net book value of property, plant and equipment located within the PRC was $61.7 million and $76.4 million on December 31, 2019 and 2018, respectively. The net book value of property, plant and equipment located in Mexico was $13.6 million and $3.3 million on December 31, 2019 and 2018, respectively.

During the year ended December 31, 2018, we incurred $2.9 million in impairment on tooling and equipment as a result of the transition of manufacturing operations between our PRC-based manufacturing facilities following the closure of our Guangzhou factory, which was sold in 2018. We incurred an additional $0.1 million and $2.0 million of impairment on factory equipment during the years ended December 31, 2019 and 2018, respectively, as a result of the transition of certain manufacturing operations out of the PRC in response to tariffs enacted in the U.S. in 2018 on certain products manufactured in the PRC and imported into the U.S. These impairment charges, aggregating to $0.1 million and $4.9 million, are recorded within cost of goods sold for the year ended December 31, 2019 and 2018, respectively.

Construction in progress was as follows:



	December 31,
(In thousands)	2019		2018
Machinery and equipment	1,428		2,444
Tooling	759		1,581
Leasehold and building improvements	574		675
Software	518		352
Other	319		504
Total construction in progress	$	3,598	$	5,556

We expect that most of the assets under construction will be placed into service during the first six months of 2020. We will begin to depreciate the cost of these assets under construction once they are placed into service.

Long-lived tangible assets by geographic area were as follows:



	December 31,
(In thousands)	2019		2018
United States	$	13,016	$	14,504
People's Republic of China	62,148		79,382
Mexico	13,673		3,362
All other countries	4,058		3,207
Total long-lived tangible assets	$	92,895	$	100,455