Cross-border trade dropped in the first 11 months in line with sluggish exports, the global economic slowdown, the strong baht and the US-China trade war.
The Commerce Ministry's Foreign Trade Department said the country's overall cross-border trade, including transit trade, totalled 1.23 trillion baht for the year to November, down 3% from the same period last year.
Transit trade consists of businesses involved in the passage of goods through more than one country.
Of the total figures, exports from Thailand accounted for 687.40 billion baht, down 2.6% from the first 11 months of last year, while imports totalled 544.45 billion baht, down 3.4%, yielding a trade surplus of 142.94 billion baht.
Border trade with Thailand's four nearest neighbours amounted to 985.11 billion baht, down 4% from the first 11 months of last year, with exports making up 560.07 billion baht, down 5.5%.
Imports were worth 425.03 billion baht, down 2.1%. Thailand secured a trade surplus worth 135.04 billion baht with the four nations.
Malaysia remained the biggest partner for border trade, with two-way trade reaching 476.15 billion baht, down 8.7%, followed by Laos (181.80 billion baht), Myanmar (180.73 billion baht) and Cambodia (146.41 billion baht).
The department reported that transit trade with Singapore, Vietnam and southern China remained on the rise in the period, totalling 246.78 billion baht, up 1.5%. Exports rose by 12.2% to 127.32 billion baht, while imports dipped 7.9% to 119.42 billion baht.
Transit trade to southern China fetched the greatest value (118.58 billion baht), followed by Singapore (67.66 billion baht) and Vietnam (60.5 billion baht).
Keerati Rushchano, the department's director-general, said border trade struggled alongside the country's exports, which plunged 2.8% year-on-year in the first 11 months of 2019.